[linux-lvm] LVM questions

[linux-lvm] LVM questions

[Eric A. Hall]

Hi guys,

I'm putting together a storage server for NAS and iSCSI purposes and am
looking to use LVM for some or all of this. I've read up on LVM but I
still have some basic newbie questions for this.

I've got a bunch of Raptor 150 ADFD drives and a 3Ware 9650SE board
providing the basic back-end storage (currently RAID-5 but will move to
RAID-6 soon, with estimated capacity of approx 800-900 GB, although the
entire array may shrink or grow as projects demand). The opsys root
partition will be about 40 GB XFS, with another 4GB swap partition, and
the NAS/storage pool will be about 300 GB XFS, with the remainder of the
space being used by the iSCSI volumes (about another 300 GB, divvied up
among different iSCSI LUNs). I want to be able to shrink and expand these
by about 10 GB per (although swap may only change by +/-4GB) so I figure
I'll use LVM for all of the partitions. A couple of other considerations
here: I need to align the partitions on page boundaries for iSCSI
performance reasons, and I am also thinking about managing blockdev
read-ahead differently for each of the final volumes.

I assume that a single physical extent across /dev/sda will work as well
as anything else here. Will having more partitions make it easier to
shrink and expand the whole RAID if that ever becomes necessary? Anything
else I should take into consideration?

Should I create a single volume group or should I create multiple volume
groups, or does it even matter? What are the issues?

I have seen some people talk about creating hundreds of small partitions
and using those for moving and resizing. Is this needed, desirable, or
just a stupid human trick?

Anything else I should take into consideration here would be appreciated

Thanks!

Re: [linux-lvm] LVM questions

[Stuart D. Gathman]

On Thu, 29 Mar 2007, Eric A. Hall wrote:

> I have seen some people talk about creating hundreds of small partitions
> and using those for moving and resizing. Is this needed, desirable, or
> just a stupid human trick?

That is a work around for lack of functionality in LVM.  Having used
LVM on AIX, that is the gold standard for me.  The LVM divides into
little partitions and keeps track of them for you.  So why do it 
manually?  Using md for mirroring, each partition synchronizes separately.
Manually making several smaller partitions lets you move them around and resync
- all while the system is running.  This happens automatically when LVM
supports mirroring, but LVM mirroring is still a new experimental feature
on linux.

Multiple volume groups just get in the way when you are resizing and
migrating between physical volumes.  You need a separate volume group
when you need to physically pick up the entire volume group and 
take it somewhere else.  For instance, scientific datasets are
often much too large (terabytes) for DVD, tape, or internet.  So, just make a
volume group on a handful of 500G drives, build and process your data
there, then deactivate the VG and send the drives to your colleague
(make a copy first, of course).  Your colleague plugs the drives into
his USB/SATA/iSCSI/whatever controller, activates the volume group,
and now has a copy of your work.

For anything that will never be physically moved to another machine, keep
it all on one volume group.  But, for instance, if you think you might
want to move the iSCSI data to another box at some point, keep it 
in its own VG (with its own set of drives) to make that easy.

-- 
	      Stuart D. Gathman <stuart@bmsi.com>
    Business Management Systems Inc.  Phone: 703 591-0911 Fax: 703 591-6154
"Confutatis maledictis, flammis acribus addictis" - background song for
a Microsoft sponsored "Where do you want to go from here?" commercial.

Re: [linux-lvm] LVM questions

[Nix]

On 29 Mar 2007, Stuart D. Gathman said:
> For anything that will never be physically moved to another machine, keep
> it all on one volume group.  But, for instance, if you think you might
> want to move the iSCSI data to another box at some point, keep it 
> in its own VG (with its own set of drives) to make that easy.

I also use VGs when I have several classes of PV with radically
different properties (especially failure properties) and want to be sure
that the failure of one PV can't possibly affect the LVs on the devices
with other failure properties.

At one point I had three VGs on one of my systems. One spanned PVs on
top of a RAID-5 md array. That array was composed of disks of radically
different sizes, so I had another VG spanning PVs consuming all that
slack space. Then, for testing purposes, I had another VG sitting
entirely atop the network block device.

The NBDed VG could be expected to go down fairly frequently (as NBD
connections don't outlast server reboots), but I didn't want that to
affect either of the local VGs. The non-RAIDed VG might fail if a single
disk dies, but that only had news spool and caches on it so I didn't
want it to affect the important stuff on the RAIDed VGs.

Hence, three VGs made considerable sense.

[linux-lvm] LVM Questions

[Nicholas Muguira]

[-- Attachment #1: Type: text/plain, Size: 2005 bytes --]

I am trying to judge the ability of LVM to address a problem I currently
have, and I have few questions:

 

1)       Is there a way to configure LVM so that the data on remaining
PV's in a VG are is accessible after a PV fails?

2)       Is there a way to configure LVM so that the LV will still be
accesible and readable/writable if a PV fails while in use?

3)       Assuming groupings of external drives, can a LV be created and
exported on each group of the same name and then imported into different
systems. For example assuming 10 drives, drives a-e are in group 1 and
drives f-j are in group 2. Using System A with drives a-e connect to
/dev/sda-e create a parittion that spans the entire drive for each
drive. Create a PV on each partition (/dev/sd[a-e]1). Create a VG named
test with all partitions (/dev/sd[a-e]1). Create a LV that covers all of
the VG test. Mount the LV and format it (ext3 in this case). Umount and
vgexport the vg test. Repeat the steps with drives f-j with same VG and
LV names. Connect group 1 to System B and vgimport VG test, create LV
with it and mount the filesystem. Umount the filesystem and disconnect
group1. Connect group 2 to System B and vgimport VG test and mount the
filesystem (using LV previously created)?

 

Raid is unavailable due to already deployed hardware, and I realize that
LVM is not Raid and will not give me a means to recover the data on the
failed HDD.

 

Thanks,
Nick

This email and any files transmitted with it are confidential and are intended solely for the use of the individual or entity to whom they are addressed.  If you are not the original recipient or the person responsible for delivering the email to the intended recipient, be advised that you have received this email in error, and that any use, dissemination, forwarding, printing, or copying of this email is strictly prohibited. If you received this email in error, please immediately notify the sender and delete the original.



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Re: [linux-lvm] LVM Questions

[Jordi Prats]

Hi,
You could still use raid using pvmove: You could create a raid and then 
use pvmove to relocate data present on your disk to your new raid device.

cheers,
Jordi


Nicholas Muguira wrote:
>
> I am trying to judge the ability of LVM to address a problem I 
> currently have, and I have few questions:
>
> 1) Is there a way to configure LVM so that the data on remaining PV�s 
> in a VG are is accessible after a PV fails?
>
> 2) Is there a way to configure LVM so that the LV will still be 
> accesible and readable/writable if a PV fails while in use?
>
> 3) Assuming groupings of external drives, can a LV be created and 
> exported on each group of the same name and then imported into 
> different systems. For example assuming 10 drives, drives a-e are in 
> group 1 and drives f-j are in group 2. Using System A with drives a-e 
> connect to /dev/sda-e create a parittion that spans the entire drive 
> for each drive. Create a PV on each partition (/dev/sd[a-e]1). Create 
> a VG named test with all partitions (/dev/sd[a-e]1). Create a LV that 
> covers all of the VG test. Mount the LV and format it (ext3 in this 
> case). Umount and vgexport the vg test. Repeat the steps with drives 
> f-j with same VG and LV names. Connect group 1 to System B and 
> vgimport VG test, create LV with it and mount the filesystem. Umount 
> the filesystem and disconnect group1. Connect group 2 to System B and 
> vgimport VG test and mount the filesystem (using LV previously created)?
>
> Raid is unavailable due to already deployed hardware, and I realize 
> that LVM is not Raid and will not give me a means to recover the data 
> on the failed HDD.
>
> Thanks,
> Nick
>
> This email and any files transmitted with it are confidential and are 
> intended solely for the use of the individual or entity to whom they 
> are addressed. If you are not the original recipient or the person 
> responsible for delivering the email to the intended recipient, be 
> advised that you have received this email in error, and that any use, 
> dissemination, forwarding, printing, or copying of this email is 
> strictly prohibited. If you received this email in error, please 
> immediately notify the sender and delete the original.
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com
> https://www.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/


-- 
......................................................................
         __
        / /          Jordi Prats
  C E / S / C A      Dept. de Sistemes
      /_/            Centre de Supercomputaci� de Catalunya

  Gran Capit�, 2-4 (Edifici Nexus) � 08034 Barcelona
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...................................................................... 

[linux-lvm] LVM Questions

[Darren Young]

I have only recently discovered and played with LVM.
If anyone can answer some general questions, it would
be most appreciated.

What I would like to have is a system where I can add
space via new disks and expand file systems at will. I
have used volume managers on HP and Solaris for
precisely these purposes (HP and Veritas). Too many
times I have been called by a customer or a customer
of a friend with the "I underestimated the space
needed for my Oracle databases and I need space,
now!". Adding disks and placing db's on alternate
filesystems gets the job done, but an LVM would be a
great method to move them to.

First, does LVM do RAID or do I need to employ the md
driver to accomplish this? It seems to me (as a
sysadmin) that LVM is great for adding space when
needed, but having RAID capabilities in conjunction
with this would be required to produce a highly
available system.

What ext2 resize utility is the ideal choice for LVM
to use. parted seems to be quite functional, but
having to down the machine to single is a but
annoying. Has anyone successfully used the ext2online
utility on RedHat? It seems as though the version of
e2fsprogs that includes this code is part of RH 7.1
anyways. At least from what I can tell. The online
resizing would definitely be required for a highly
available system as well.

I started with RedHat 7.1 with the 2.4.2 kernel and
patched it. What kernel is ideal to use with LVM? This
one seems to work, but I read a reference in the list
archive that certain components are in 2.4. Is this
the case?

The howto mentions to add a couple of commands to the
RH start script, but a scan of them reveals that RH
7.1 already has them. If they are correct, perhaps the
howto needs to reflect this. Does anyone know if they
are correct?

I picked up on an older thread about the mailing list
rejecting certain email and just had to dump in my .02
worth. I don't want to start a war, but the list
should be completely open. I remember the FreeSWAN
list having wars over open vs closed and open won. The
maintainers are of the opinion (from what I read) that
filtering spam is up to the user and cleaning of any
type of a list is censoring. I had to get that out
since I will most likely be using this product
somewhere down the road.

I also read an older thread on an X11 GUI as well as
some replies to it. The GUI that comes with Veritas is
completely useless and the command line tools are
completely over-engineered. While it would be nice for
a small company trying to save money not to call in a
specialist to create VG's, it certainly wouldn't be a
requirement. Get everything stable, reliable and
consistent than someone will probably have the time to
create the GUI. I'd dedicate time to that type of
project, but why bother when the code isn't quite
there yet. There's no reason.

Guess that's a total of .04 cents...

Thanks in advance,

Darren Young
Senior UNIX Administrator
GSX.com

__________________________________________________
Do You Yahoo!?
Yahoo! Auctions - buy the things you want at great prices
http://auctions.yahoo.com/

Re: [linux-lvm] LVM Questions

[Glenn Shannon]

Note: Comments interspersed in email.

Darren Young wrote:

> I have only recently discovered and played with LVM.
> If anyone can answer some general questions, it would
> be most appreciated.
>
> What I would like to have is a system where I can add
> space via new disks and expand file systems at will. I
> have used volume managers on HP and Solaris for
> precisely these purposes (HP and Veritas). Too many
> times I have been called by a customer or a customer
> of a friend with the "I underestimated the space
> needed for my Oracle databases and I need space,
> now!". Adding disks and placing db's on alternate
> filesystems gets the job done, but an LVM would be a
> great method to move them to.

Well, I just added a partition off of a 40GB drive I just acquired to my
existing LVM without a hitch.
And using reiserfs I can resize the filesystem(s) to acquire the new
space and place it where it needs to be.


> First, does LVM do RAID or do I need to employ the md
> driver to accomplish this? It seems to me (as a
> sysadmin) that LVM is great for adding space when
> needed, but having RAID capabilities in conjunction
> with this would be required to produce a highly
> available system.

As far as I can tell I have gotten maybe a 10% increase by adding the
other hard drive (which sits on its own Promise controller) so I am not
sure at this point whether I created a pseudo-RAID 0 or not (I think
not).

That would be a great feature to have though! But with Linux already
having software raid, I don't see it becoming a priority of the
programmers to re-invent the wheel before they finish building on what
they have right now...my .02 worth.


> What ext2 resize utility is the ideal choice for LVM
> to use. parted seems to be quite functional, but
> having to down the machine to single is a but
> annoying. Has anyone successfully used the ext2online
> utility on RedHat? It seems as though the version of
> e2fsprogs that includes this code is part of RH 7.1
> anyways. At least from what I can tell. The online
> resizing would definitely be required for a highly
> available system as well.

I use parted myself. FDisk is broken on my machine for some strange
reason known only to God. It keeps picking up some darned
4.2BSD partitioning schema. sfdisk and cfdisk work fine, and so does
parted.


> I started with RedHat 7.1 with the 2.4.2 kernel and
> patched it. What kernel is ideal to use with LVM? This
> one seems to work, but I read a reference in the list
> archive that certain components are in 2.4. Is this
> the case?

I am using 2.4.4 but I think I will regress back to 2.4.3 in light of
some technical difficulties I am having...but will have to wait till my
next scheduled reboot for that. I work with this stuff on a development
machine used by other people :)

By the way *they* like the changes too.....I can dynamically resize
their home partitions to accomodate their needs *without* rebooting.


> The howto mentions to add a couple of commands to the
> RH start script, but a scan of them reveals that RH
> 7.1 already has them. If they are correct, perhaps the
> howto needs to reflect this. Does anyone know if they
> are correct?

The vgscan and vgchange lines are installed by default on RedHat 7.1?
Interesting.


> I picked up on an older thread about the mailing list
> rejecting certain email and just had to dump in my .02
> worth. I don't want to start a war, but the list
> should be completely open. I remember the FreeSWAN
> list having wars over open vs closed and open won. The
> maintainers are of the opinion (from what I read) that
> filtering spam is up to the user and cleaning of any
> type of a list is censoring. I had to get that out
> since I will most likely be using this product
> somewhere down the road.

I agree. Censorship is bad when we don't do it for ourselves.


> I also read an older thread on an X11 GUI as well as
> some replies to it. The GUI that comes with Veritas is
> completely useless and the command line tools are
> completely over-engineered. While it would be nice for
> a small company trying to save money not to call in a
> specialist to create VG's, it certainly wouldn't be a
> requirement. Get everything stable, reliable and
> consistent than someone will probably have the time to
> create the GUI. I'd dedicate time to that type of
> project, but why bother when the code isn't quite
> there yet. There's no reason.

I agree again. Good point. Although, I would like to interject my
opinion that it seems pretty darned stable right now. I can't wait to
see what these guys are going to do next!


> Guess that's a total of .04 cents...
>
> Thanks in advance,
>
> Darren Young
> Senior UNIX Administrator
> GSX.com
>
> __________________________________________________
> Do You Yahoo!?
> Yahoo! Auctions - buy the things you want at great prices
> http://auctions.yahoo.com/
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@sistina.com
> http://lists.sistina.com/mailman/listinfo/linux-lvm

Re: [linux-lvm] LVM Questions

[Evan Day]

Darren Young wrote:
> First, does LVM do RAID or do I need to employ the md
> driver to accomplish this? It seems to me (as a
> sysadmin) that LVM is great for adding space when
> needed, but having RAID capabilities in conjunction
> with this would be required to produce a highly
> available system.

LVM doesn't do RAID right now - you can use either a hardware
RAID or the kernel's built-in RAID support (raid 0, 1, and 5).

> What ext2 resize utility is the ideal choice for LVM
> to use. parted seems to be quite functional, but
> having to down the machine to single is a but
> annoying. Has anyone successfully used the ext2online
> utility on RedHat? It seems as though the version of
> e2fsprogs that includes this code is part of RH 7.1
> anyways. At least from what I can tell. The online
> resizing would definitely be required for a highly
> available system as well.

I don't have much experience with ext2 resizing, but the
reiserfs can easily be extended.  I'm not sure if it is
supported or not, but I've actually extended filesystems
while mounted with no ill effects.

Reiserfs support is built in to kernel 2.4.X.

> I started with RedHat 7.1 with the 2.4.2 kernel and
> patched it. What kernel is ideal to use with LVM? This
> one seems to work, but I read a reference in the list
> archive that certain components are in 2.4. Is this
> the case?

The 2.4.X kernel contains base LVM support, but you'll need
to supplement that with patches at the same level as the
LVM user-level tools.  Current release is 0.9.1b7.

> I also read an older thread on an X11 GUI as well as
> some replies to it. The GUI that comes with Veritas is
> completely useless and the command line tools are
> completely over-engineered. While it would be nice for
> a small company trying to save money not to call in a
> specialist to create VG's, it certainly wouldn't be a
> requirement. Get everything stable, reliable and
> consistent than someone will probably have the time to
> create the GUI. I'd dedicate time to that type of
> project, but why bother when the code isn't quite
> there yet. There's no reason.

LVM is so simple that, IMHO, a GUI shouldn't be an overriding
concern.  Then again, I've been working with LVM on HP-UX
for many years, and I find the CLI utilities to be much
more efficient than waiting for SAM (the HP-UX sysadmin
GUI) to poll everything, build displays, etc.  The current
CLI tools are lean and aligned with the LVM model in a
way that is both logical and easy to understand.

Re: [linux-lvm] LVM Questions

[Adrian Phillips]

>>>>> "Evan" == Evan Day <banal@home.com> writes:

<snip>

    >> What ext2 resize utility is the ideal choice for LVM to
    >> use. parted seems to be quite functional, but having to down
    >> the machine to single is a but annoying. Has anyone
    >> successfully used the ext2online utility on RedHat? It seems as
    >> though the version of e2fsprogs that includes this code is part
    >> of RH 7.1 anyways. At least from what I can tell. The online
    >> resizing would definitely be required for a highly available
    >> system as well.

    Evan> I don't have much experience with ext2 resizing, but the

I haven't either.

    Evan> reiserfs can easily be extended.  I'm not sure if it is
    Evan> supported or not, but I've actually extended filesystems
    Evan> while mounted with no ill effects.

I believe it is officially supported, ie. if it breaks then its a bug,
and have done it now several times, at least on lightly loaded
filesystems. Its not quite as convienient as AIX's LVM, in that one
resizes the filesystem and the logical volume is automatically
resized, but if I'm bothered I'll write a wrapper script around
lvextend/lvreduce for that.

A question for the developers if they notice. Why lvextend and
lvreduce, as they do the same things. Is it just for clarity ? A
lvresize with + or - or a fixed size to could the same ?

<snip>

    >> I also read an older thread on an X11 GUI as well as some
    >> replies to it. The GUI that comes with Veritas is completely
    >> useless and the command line tools are completely
    >> over-engineered. While it would be nice for a small company
    >> trying to save money not to call in a specialist to create
    >> VG's, it certainly wouldn't be a requirement. Get everything
    >> stable, reliable and consistent than someone will probably have
    >> the time to create the GUI. I'd dedicate time to that type of
    >> project, but why bother when the code isn't quite there
    >> yet. There's no reason.

    Evan> LVM is so simple that, IMHO, a GUI shouldn't be an
    Evan> overriding concern.  Then again, I've been working with LVM
    Evan> on HP-UX for many years, and I find the CLI utilities to be
    Evan> much more efficient than waiting for SAM (the HP-UX sysadmin
    Evan> GUI) to poll everything, build displays, etc.  The current
    Evan> CLI tools are lean and aligned with the LVM model in a way
    Evan> that is both logical and easy to understand.

On the web page there is a BETA lva, written in perl-tk which works
nicely although somewhat limited currently. I like the pie chart look,
not for me personally, CLI type myself, but for some of the others at
work who must have a GUI for everything, yukk :-)

Sincerely,

Adrian Phillips

-- 
Your mouse has moved.
Windows NT must be restarted for the change to take effect.
Reboot now?  [OK]

Re: [linux-lvm] LVM Questions

[Heinz J. Mauelshagen]

On Thu, May 03, 2001 at 08:56:00AM +0200, Adrian Phillips wrote:
> >>>>> "Evan" == Evan Day <banal@home.com> writes:
> 
> <snip>
> 
>     >> What ext2 resize utility is the ideal choice for LVM to
>     >> use. parted seems to be quite functional, but having to down
>     >> the machine to single is a but annoying. Has anyone
>     >> successfully used the ext2online utility on RedHat? It seems as
>     >> though the version of e2fsprogs that includes this code is part
>     >> of RH 7.1 anyways. At least from what I can tell. The online
>     >> resizing would definitely be required for a highly available
>     >> system as well.
> 
>     Evan> I don't have much experience with ext2 resizing, but the
> 
> I haven't either.
> 
>     Evan> reiserfs can easily be extended.  I'm not sure if it is
>     Evan> supported or not, but I've actually extended filesystems
>     Evan> while mounted with no ill effects.
> 
> I believe it is officially supported, ie. if it breaks then its a bug,
> and have done it now several times, at least on lightly loaded
> filesystems. Its not quite as convienient as AIX's LVM, in that one
> resizes the filesystem and the logical volume is automatically
> resized, but if I'm bothered I'll write a wrapper script around
> lvextend/lvreduce for that.
> 
> A question for the developers if they notice. Why lvextend and
> lvreduce, as they do the same things. Is it just for clarity ? A
> lvresize with + or - or a fixed size to could the same ?

The Linux LVM CLI is as close as possible to the HP/UX one which has
those commands (and vgextend/vgreduce as well) seperate.
This makes at least me as a long term HP/UX LVM user happy ;-)

lvresize can easily be made as a convenence wrapper though...

> 
> <snip>
> 
>     >> I also read an older thread on an X11 GUI as well as some
>     >> replies to it. The GUI that comes with Veritas is completely
>     >> useless and the command line tools are completely
>     >> over-engineered. While it would be nice for a small company
>     >> trying to save money not to call in a specialist to create
>     >> VG's, it certainly wouldn't be a requirement. Get everything
>     >> stable, reliable and consistent than someone will probably have
>     >> the time to create the GUI. I'd dedicate time to that type of
>     >> project, but why bother when the code isn't quite there
>     >> yet. There's no reason.
> 
>     Evan> LVM is so simple that, IMHO, a GUI shouldn't be an
>     Evan> overriding concern.  Then again, I've been working with LVM
>     Evan> on HP-UX for many years, and I find the CLI utilities to be
>     Evan> much more efficient than waiting for SAM (the HP-UX sysadmin
>     Evan> GUI) to poll everything, build displays, etc.  The current
>     Evan> CLI tools are lean and aligned with the LVM model in a way
>     Evan> that is both logical and easy to understand.
> 
> On the web page there is a BETA lva, written in perl-tk which works
> nicely although somewhat limited currently. I like the pie chart look,
> not for me personally, CLI type myself, but for some of the others at
> work who must have a GUI for everything, yukk :-)
> 
> Sincerely,
> 
> Adrian Phillips
> 
> -- 
> Your mouse has moved.
> Windows NT must be restarted for the change to take effect.
> Reboot now?  [OK]
> _______________________________________________
> linux-lvm mailing list
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Regards,
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    Nevertheless it needs not so stupid people to solve them ***

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Heinz Mauelshagen                                 Sistina Software Inc.
Senior Consultant/Developer                       Am Sonnenhang 11
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Re: [linux-lvm] LVM Questions

[Adrian Phillips]

>>>>> "Heinz" == Heinz J Mauelshagen <Mauelshagen@sistina.com> writes:

<snip>
    >>  I believe it is officially supported, ie. if it breaks then
    >> its a bug, and have done it now several times, at least on
    >> lightly loaded filesystems. Its not quite as convienient as
    >> AIX's LVM, in that one resizes the filesystem and the logical
    >> volume is automatically resized, but if I'm bothered I'll write
    >> a wrapper script around lvextend/lvreduce for that.
    >> 
    >> A question for the developers if they notice. Why lvextend and
    >> lvreduce, as they do the same things. Is it just for clarity ?
    >> A lvresize with + or - or a fixed size to could the same ?

    Heinz> The Linux LVM CLI is as close as possible to the HP/UX one
    Heinz> which has those commands (and vgextend/vgreduce as well)
    Heinz> seperate.  This makes at least me as a long term HP/UX LVM
    Heinz> user happy ;-)

HP/UX, how unfortunate :-) Thanks for the info. though.

    Heinz> lvresize can easily be made as a convenence wrapper
    Heinz> though...

Patches accepted I presume :-)

Sincerely,

Adrian Phillips

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Re: [linux-lvm] LVM Questions

[Heinz J. Mauelshagen]

On Fri, May 04, 2001 at 09:45:24AM +0200, Adrian Phillips wrote:
> >>>>> "Heinz" == Heinz J Mauelshagen <Mauelshagen@sistina.com> writes:
> 
> <snip>
>     >>  I believe it is officially supported, ie. if it breaks then
>     >> its a bug, and have done it now several times, at least on
>     >> lightly loaded filesystems. Its not quite as convienient as
>     >> AIX's LVM, in that one resizes the filesystem and the logical
>     >> volume is automatically resized, but if I'm bothered I'll write
>     >> a wrapper script around lvextend/lvreduce for that.

True.

JAIOOTL (Just Another Item On Our Todo List ;-)

>     >> 
>     >> A question for the developers if they notice. Why lvextend and
>     >> lvreduce, as they do the same things. Is it just for clarity ?
>     >> A lvresize with + or - or a fixed size to could the same ?
> 
>     Heinz> The Linux LVM CLI is as close as possible to the HP/UX one
>     Heinz> which has those commands (and vgextend/vgreduce as well)
>     Heinz> seperate.  This makes at least me as a long term HP/UX LVM
>     Heinz> user happy ;-)
> 
> HP/UX, how unfortunate :-) Thanks for the info. though.

;-)

Actually the HP/UX LVM and its CLI has some major advantages over others:

 - it has a very simple layering (the PV, VG, LV thingies) and therefore
   is very easy to understand

 - the CLI follows the layers transparently

 - CLI is "self explaining" in regard of having native language
   postfixes in the command names like create, extend, reduce, change etc.

In production this boils down to shorter learning cycles for admin newbies
and easier handling in regular production -> less money spend!

BTW: what's unfortunate IYO with the HP/UX LVM? :-)

> 
>     Heinz> lvresize can easily be made as a convenence wrapper
>     Heinz> though...
> 
> Patches accepted I presume :-)

You can read between lines.
I like that ;-)

> 
> Sincerely,
> 
> Adrian Phillips
> 
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Regards,
Heinz    -- The LVM Guy --

*** Software bugs are stupid.
    Nevertheless it needs not so stupid people to solve them ***

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Heinz Mauelshagen                                 Sistina Software Inc.
Senior Consultant/Developer                       Am Sonnenhang 11
                                                  56242 Marienrachdorf
                                                  Germany
Mauelshagen@Sistina.com                           +49 2626 141200
                                                       FAX 924446
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Re: [linux-lvm] LVM Questions

[Adrian Phillips]

>>>>> "Heinz" == Heinz J Mauelshagen <Mauelshagen@sistina.com> writes:

<snip>

    >>  HP/UX, how unfortunate :-) Thanks for the info. though.

    Heinz> ;-)

    Heinz> Actually the HP/UX LVM and its CLI has some major
    Heinz> advantages over others:

    Heinz>  - it has a very simple layering (the PV, VG, LV thingies)
    Heinz> and therefore is very easy to understand

    Heinz>  - the CLI follows the layers transparently

    Heinz>  - CLI is "self explaining" in regard of having native
    Heinz> language postfixes in the command names like create,
    Heinz> extend, reduce, change etc.

    Heinz> In production this boils down to shorter learning cycles
    Heinz> for admin newbies and easier handling in regular production
    Heinz> -> less money spend!

Actually I thought that LVM had been modelled upon AIX's LVM when I
first started using it; the commands are very similar.

Actually, it gives me an idea for AIX compatiblity wrappers (possibly
something else for the TODO list if it hasn't filled up the LV
already, then again you can always lvextend it:-)

    Heinz> BTW: what's unfortunate IYO with the HP/UX LVM? :-)

Sorry, I meant HP/UX OS itself (not from personal experience but the
years of reading of non-standard HP/UX command, libraries, etc., then
again AIX has had it share of those).

<snip>

Anyway, thats to you and others who had a hand in LVM. It makes
using Linux as easy (on the FS side) as its been to use AIX for the
years I've admining it (almost 10 now).

Regards,

Adrian

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Re: [linux-lvm] LVM Questions

[Heinz J. Mauelshagen]

On Fri, May 04, 2001 at 11:38:43AM +0200, Adrian Phillips wrote:
> >>>>> "Heinz" == Heinz J Mauelshagen <Mauelshagen@sistina.com> writes:
> 
> <snip>
> 
>     >>  HP/UX, how unfortunate :-) Thanks for the info. though.
> 
>     Heinz> ;-)
> 
>     Heinz> Actually the HP/UX LVM and its CLI has some major
>     Heinz> advantages over others:
> 
>     Heinz>  - it has a very simple layering (the PV, VG, LV thingies)
>     Heinz> and therefore is very easy to understand
> 
>     Heinz>  - the CLI follows the layers transparently
> 
>     Heinz>  - CLI is "self explaining" in regard of having native
>     Heinz> language postfixes in the command names like create,
>     Heinz> extend, reduce, change etc.
> 
>     Heinz> In production this boils down to shorter learning cycles
>     Heinz> for admin newbies and easier handling in regular production
>     Heinz> -> less money spend!
> 
> Actually I thought that LVM had been modelled upon AIX's LVM when I
> first started using it; the commands are very similar.

That's possible easy because both have common roots :-)

> 
> Actually, it gives me an idea for AIX compatiblity wrappers (possibly
> something else for the TODO list if it hasn't filled up the LV
> already, then again you can always lvextend it:-)
> 
>     Heinz> BTW: what's unfortunate IYO with the HP/UX LVM? :-)
> 
> Sorry, I meant HP/UX OS itself (not from personal experience but the
> years of reading of non-standard HP/UX command, libraries, etc., then
> again AIX has had it share of those).

No problem.
Thanks for the clarification.

> 
> <snip>
> 
> Anyway, thats to you and others who had a hand in LVM. It makes
> using Linux as easy (on the FS side) as its been to use AIX for the
> years I've admining it (almost 10 now).
> 
> Regards,
> 
> Adrian
> 
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Regards,
Heinz    -- The LVM Guy --

*** Software bugs are stupid.
    Nevertheless it needs not so stupid people to solve them ***

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Heinz Mauelshagen                                 Sistina Software Inc.
Senior Consultant/Developer                       Am Sonnenhang 11
                                                  56242 Marienrachdorf
                                                  Germany
Mauelshagen@Sistina.com                           +49 2626 141200
                                                       FAX 924446
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Re: [linux-lvm] LVM Questions

[Heinz J. Mauelshagen]

On Wed, May 02, 2001 at 06:45:59PM -0700, Evan Day wrote:
> Darren Young wrote:
> > First, does LVM do RAID or do I need to employ the md
> > driver to accomplish this? It seems to me (as a
> > sysadmin) that LVM is great for adding space when
> > needed, but having RAID capabilities in conjunction
> > with this would be required to produce a highly
> > available system.
> 
> LVM doesn't do RAID right now - you can use either a hardware
> RAID or the kernel's built-in RAID support (raid 0, 1, and 5).

Evan is right for RAID > 0.

RAID 0 is supported in Linux LVM natively.

You could for eg. address your availability needs with MD or hardware RAID
*and* your performance needs at the same time by setting up RAID 0 logical
volumes striped over a bunch of RAID subsystem based physical volumes.

> 
> > What ext2 resize utility is the ideal choice for LVM
> > to use. parted seems to be quite functional, but
> > having to down the machine to single is a but
> > annoying. Has anyone successfully used the ext2online
> > utility on RedHat? It seems as though the version of
> > e2fsprogs that includes this code is part of RH 7.1
> > anyways. At least from what I can tell. The online
> > resizing would definitely be required for a highly
> > available system as well.
> 
> I don't have much experience with ext2 resizing, but the
> reiserfs can easily be extended.  I'm not sure if it is
> supported or not, but I've actually extended filesystems
> while mounted with no ill effects.
> 
> Reiserfs support is built in to kernel 2.4.X.

WRT ext2 you could give Andreas Dilger's ext2resize GNU software a try.

Please look for it at http://ext2resize.sourceforge.net/.

> 
> > I started with RedHat 7.1 with the 2.4.2 kernel and
> > patched it. What kernel is ideal to use with LVM? This
> > one seems to work, but I read a reference in the list
> > archive that certain components are in 2.4. Is this
> > the case?
> 
> The 2.4.X kernel contains base LVM support, but you'll need
> to supplement that with patches at the same level as the
> LVM user-level tools.  Current release is 0.9.1b7.

FYI: You can get the actual GNU LVM code at www.sistina.com/lvm.

> 
> > I also read an older thread on an X11 GUI as well as
> > some replies to it. The GUI that comes with Veritas is
> > completely useless and the command line tools are
> > completely over-engineered. While it would be nice for
> > a small company trying to save money not to call in a
> > specialist to create VG's, it certainly wouldn't be a
> > requirement. Get everything stable, reliable and
> > consistent than someone will probably have the time to
> > create the GUI. I'd dedicate time to that type of
> > project, but why bother when the code isn't quite
> > there yet. There's no reason.
> 
> LVM is so simple that, IMHO, a GUI shouldn't be an overriding
> concern.  Then again, I've been working with LVM on HP-UX
> for many years, and I find the CLI utilities to be much
> more efficient than waiting for SAM (the HP-UX sysadmin
> GUI) to poll everything, build displays, etc.  The current
> CLI tools are lean and aligned with the LVM model in a
> way that is both logical and easy to understand.

Thanks for the flowers :-)

Actually there are GUI contributions out there.
For eg. http://www.xs4all.nl/~mmj/lvm/ is worth trying in order to have
the day by day LVM work items covered.

BTW: Evan is touching another major point here, which people tend to forget
easily IMHO; in critical operating situations where you are limited to
the command line (single user) you *need* to be familiar with the CLI in order
to get back to regular operation as fast as possible!

> _______________________________________________
> linux-lvm mailing list
> linux-lvm@sistina.com
> http://lists.sistina.com/mailman/listinfo/linux-lvm

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Regards,
Heinz    -- The LVM Guy --

*** Software bugs are stupid.
    Nevertheless it needs not so stupid people to solve them ***

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Heinz Mauelshagen                                 Sistina Software Inc.
Senior Consultant/Developer                       Am Sonnenhang 11
                                                  56242 Marienrachdorf
                                                  Germany
Mauelshagen@Sistina.com                           +49 2626 141200
                                                       FAX 924446
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Re: [linux-lvm] LVM Questions

[Carlo Marcelo Arenas Belon]

<SNIP>
> First, does LVM do RAID or do I need to employ the md
> driver to accomplish this? It seems to me (as a
> sysadmin) that LVM is great for adding space when
> needed, but having RAID capabilities in conjunction
> with this would be required to produce a highly
> available system.

for sure using RAID1 or RAID5 would make any system a highly available
one, but i am not sure if i understand what your point is on LVM not doing
RAID?

just to clarify me and hopefully all that are getting nervous with that
aseveration

you can make pseudo LINEAR or RAID0 arrays using LVM pvcreating all the
needed disks and making a VG over them.

when more space is needed on any LV all what is needed is to :

1) pvcreate the new disk/partition
2) vgextend the VG where you are short on space over the new PV
3) lvextend the LV inside the VG where you need the space
4) extend the filesystem that is on the extended LV

so, if you have (as i just happened to have)

[root@sajino /root]# pvscan
pvscan -- reading all physical volumes (this may take a while...)
pvscan -- ACTIVE   PV "/dev/hda9" of VG "vga" [10.08 GB / 0 free]
pvscan -- ACTIVE   PV "/dev/hdb"  of VG "vga" [27.96 GB / 0 free]
pvscan -- ACTIVE   PV "/dev/hdc"  of VG "vga" [19.01 GB / 5.67 GB free]
pvscan -- total: 3 [57.05 GB] / in use: 3 [57.05 GB] / in no VG: 0 [0]

[root@sajino /root]# lvscan
lvscan -- ACTIVE            "/dev/vga/vga1" [5 GB]
lvscan -- ACTIVE            "/dev/vga/vga2" [1 GB]
lvscan -- ACTIVE            "/dev/vga/vga3" [1 GB]
lvscan -- ACTIVE            "/dev/vga/vga4" [256 MB]
lvscan -- ACTIVE            "/dev/vga/vga5" [44 GB]
lvscan -- ACTIVE            "/dev/vga/vga6" [128 MB]
lvscan -- 6 logical volumes with 51.38 GB total in 1 volume group
lvscan -- 6 active logical volumes

and just on VG that is named vga.

and i need more space on vga5 (ext2) all what is needed (adding a new disk
as hdd with 30G)

  pvcreate /dev/hdd
  vgextend /dev/vga /dev/hdd
  umount /dev/vga/vga5
  e2fsadm -L+30G /dev/vga/vga5
  mount /dev/vga/vga5

or am i missing something?

> What ext2 resize utility is the ideal choice for LVM
> to use. parted seems to be quite functional, but
> having to down the machine to single is a but
> annoying. Has anyone successfully used the ext2online
> utility on RedHat? It seems as though the version of
> e2fsprogs that includes this code is part of RH 7.1
> anyways. At least from what I can tell. The online
> resizing would definitely be required for a highly
> available system as well.

on my RH7.1 server it works.

[root@sajino /root]# rpm -q e2fsprogs
e2fsprogs-1.19-4

and if using ext2 you can use (over not mounted filesystems)

[root@sajino /root]# which resize2fs
/sbin/resize2fs

<SNIP>
> The howto mentions to add a couple of commands to the
> RH start script, but a scan of them reveals that RH
> 7.1 already has them. If they are correct, perhaps the
> howto needs to reflect this. Does anyone know if they
> are correct?

well, i didn't change those lines on /etc/rc.d/rc.sysinit and my system is
doing well.

what is recommended is this patch on /etc/rc.d/init.d/halt to add the
vgscan -n call, but is not really needed AFAIK

--- initscripts-5.83/rc.d/init.d/halt.lvm	Wed Feb 28 17:18:49 2001
+++ initscripts-5.83/rc.d/init.d/halt	Thu May  3 06:49:29 2001
@@ -163,6 +163,9 @@

 [ -f /proc/bus/usb/devices ] && umount /proc/bus/usb

+# LVM shutdown
++[ -e /proc/lvm -a -x /sbin/vgchange -a -f /etc/lvmtab ] && /sbin/vgchange -a n
+
 # Remount read only anything that's left mounted.
 #echo $"Remounting remaining filesystems (if any) readonly"
 mount | awk '/ext2/ { print $3 }' | while read line; do


regards,

Carlo

Re: [linux-lvm] LVM Questions

[Mark van Walraven]

On Thu, May 03, 2001 at 06:41:39AM -0500, Carlo Marcelo Arenas Belon wrote:
> what is recommended is this patch on /etc/rc.d/init.d/halt to add the
> vgscan -n call, but is not really needed AFAIK

How important is "/sbin/vgchange" -a n at shutdown?  It seems a bad idea
if / is on an LV ...

Mark.