[linux-lvm] raid1+lvm

[linux-lvm] raid1+lvm

[galt]

perhaps I'm missing something.

Luca,
So it is or is not possible to boot a root filesystem thats inside an lvm
without a separate /boot that is either raid1 or normal? From what you
said I'd like to interpret it as you need a initrd inside the root lv...is
that the case?  If so, could I see the root= and boot= lines from your
lilo.conf? (Assuming you have this configuration)

William Blunn,
my reasoning behind wanting root in lvm is not to expand it.  I want the
raid1 for data integrity, and I would like to avoid having more than one
raid1 set on the same disks...I figure theres more overhead and there
would be more io contention than necessary (assuming that what I'm asking
for is possible). So, in a perfect world, I would have my two disks
mirrored with raid1 and then my root,swap, and whatever else I want as lv's
inside that raid1. I mean, yes it is possible to have a bunch of raid1's
on the same disks, and yes the io contention probably isnt an issue, but
what I'm trying to do seems like the most elegant solution to me at this time.

galt

Re: [linux-lvm] raid1+lvm

[Andreas Baier]

Hi,


here is a point where I would like to ask - is it really possible to 
have swap on a logical volume?
I always thought, it is only possible to have swap on a raid, perhaps 
on a soft-raid, too, but on a lvm - please help me seeing this clear.

(assuming that what I'm asking
> for is possible). So, in a perfect world, I would have my two disks
> mirrored with raid1 and then my root,swap, and whatever else I want as lv's
> inside that raid1. 


Best regards



-- 
Andreas Baier

Re: [linux-lvm] raid1+lvm

[Patrick Caulfield]

On Mon, Sep 23, 2002 at 05:05:52PM +0200, Andreas Baier wrote:
> Hi,
> 
> 
> here is a point where I would like to ask - is it really possible to 
> have swap on a logical volume?
> I always thought, it is only possible to have swap on a raid, perhaps 
> on a soft-raid, too, but on a lvm - please help me seeing this clear.
> 

I have two boxes that swap onto LVM2 volumes and have seen no problems. LVM1
should be OK too.

-- 

patrick

Re: [linux-lvm] raid1+lvm

[Theo Van Dinter]

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On Mon, Sep 23, 2002 at 04:14:59PM +0100, Patrick Caulfield wrote:
> I have two boxes that swap onto LVM2 volumes and have seen no problems. LVM1
> should be OK too.

I've swapped on a LVM1 setup before.  The only "issue" was that swap
gets enabled before the volumes are brought online, but apparently is
then attempted again after the volumes are up.  (RedHat 7.2?)

I've since taken to keeping /boot, /, and swap out of LVM since they
normally don't need to be resized, and makes the system easier to recover
in case of problems. :)

-- 
Randomly Generated Tagline:
"Well my mother was Irish...  and your father? ... wasn't ..." - The Ref

[-- Attachment #2: Type: application/pgp-signature, Size: 232 bytes --]

Re: [linux-lvm] raid1+lvm

[Gerwin Lienert]

If you act generous you may be right with

> I've since taken to keeping /boot, /, and ..

 not need to resize.

> ..swap out of LVM since they
> normally don't need to be resized, and makes the system easier to recover
> in case of problems. :)

But what do you do, when your swap becomes to small. Shure, you can start,
having one swap device outside of your lvm, but in case of increased memory
leak, you will be happy, if you can easily define another swap device on your
lvm. I did so, and for me it worked fine.


-- 
Bis dann

Gerwin

======================

Werden Sie mit uns zum "OnlineStar 2002"! Jetzt GMX w�hlen -
und tolle Preise absahnen! http://www.onlinestar.de

Re: [linux-lvm] raid1+lvm

[Wolfgang Weisselberg]

Gerwin Lienert (gerwin.lienert@gmx.de) wrote 37 lines:

> But what do you do, when your swap becomes to small.

- use a swapfile (can be on LVM) with a low priority
- use a swap partition on LVM with a low priority

> Shure, you can start,
> having one swap device outside of your lvm, but in case of increased memory
> leak, you will be happy, if you can easily define another swap device on your
> lvm. I did so, and for me it worked fine.

How about fixing the memory leak?  :-)

Anyway, in most cases HD space is cheap and you can easily
allocate 3-4 times your RAM -- if you need more, you have a
bad leak or should definitively buy more RAM.

In all other cases, you can add swap space on the fly.  And if
you have multiple fast hard disks, do make a swap space on them
all (or even better on each raid system) and use the kernel's
inbuild ability to strip over them (set the priority identical).

-Wolfgang

Re: [linux-lvm] raid1+lvm

[Andreas Baier]

Hi,

right now, I am not yet sure, if this all is ok, I´ve learned quiet a 
bit about the LVM, and I remember, that it was not suggested to use 
swap on a lvm in former times, and it doesn´t matter if it is a swap 
file or a partition, since there could be bad things when memory is 
tight. Perhaps this is problem is removed - I never used swap on a 
lvm, but I did on a software raid1.

It would be perfect if that all would work, you built a system with 
two cheap IDE-disks or scsi if you´re rich - than one can build a 
small boot partition on both disks and with the rest of the disk one 
can make a soft-raid1 with the lvm on top.

I know I can do it, so I have root and swap and data on the raid, 
accessible via the lvm.  But would it work if mem is tight and the 
system load is high or could I run into a deadlock ?

Best regards

Andreas

Wolfgang Weisselberg wrote:

> Gerwin Lienert (gerwin.lienert@gmx.de) wrote 37 lines:
> 
> 
>>But what do you do, when your swap becomes to small.
>>
> 
> - use a swapfile (can be on LVM) with a low priority
> - use a swap partition on LVM with a low priority
> 
> 


-- 
Andreas Baier

Re: [linux-lvm] raid1+lvm

[Luca Berra]

galt wrote:
> perhaps I'm missing something.
> 
> Luca,
> So it is or is not possible to boot a root filesystem thats inside an lvm
> without a separate /boot that is either raid1 or normal? From what you
> said I'd like to interpret it as you need a initrd inside the root lv...is
> that the case?  If so, could I see the root= and boot= lines from your
> lilo.conf? (Assuming you have this configuration)

This config is far from perfect, was done in a hurry and since i was not 
able to batter lilo into perfection i had to use boot=/dev/sda and do a
dd if=/dev/sda of=/dev/sdb bs=512 count=1
after running lilo

This config was tested and i was able to boot it removing the first drive.

# lilo -V
LILO version 22.3.2

# cat /etc/lilo.conf
boot=/dev/sda
map=/boot/map
vga=normal
default=linux
keytable=/boot/us.klt
lba32
prompt
nowarn
timeout=100
message=/boot/message
menu-scheme=wb:bw:wb:bw
ignore-table
password="XXXXXXX"

image=/boot/vmlinuz
         restricted
         label=linux
         root=/dev/vg00/lvol3
         initrd=/boot/initrd.img
         append="devfs=mount console=ttyS1,9600 console=tty0"
         read-only

# df
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/vg00/lvol3        3096336   1070072   1868980  37% /
/dev/vg00/lvol1         126931      8277    112101   7% /boot
/dev/vg00/lvol4        4128448   2632024   1286712  68% /home
/dev/vg00/lvol5        2064208    240884   1718468  13% /var

# swapon -s
Filename                        Type            Size    Used    Priority
/dev/vg00/lvol2                 partition       1048568 26640   -1

# cat /proc/lvm/global
LVM module LVM version 1.0.3(19/02/2002)

# fdisk -l

Disk /dev/scsi/host0/bus0/target0/lun0/disc: 255 heads, 63 sectors, 2213 
cylinders
Units = cylinders of 16065 * 512 bytes

                                  Device Boot    Start       End 
Blocks   Id  System
/dev/scsi/host0/bus0/target0/lun0/part1   *         1         7 
56196    6  FAT16
/dev/scsi/host0/bus0/target0/lun0/part2             8      2213 
17719695   fd  Linux raid autodetect

Disk /dev/scsi/host0/bus0/target1/lun0/disc: 255 heads, 63 sectors, 2213 
cylinders
Units = cylinders of 16065 * 512 bytes

                                  Device Boot    Start       End 
Blocks   Id  System
/dev/scsi/host0/bus0/target1/lun0/part1   *         1         7 
56196    6  FAT16
/dev/scsi/host0/bus0/target1/lun0/part2             8      2213 
17719695   fd  Linux raid autodetect

# cat /etc/raidtab
raiddev /dev/md0
   raid-level 1
   nr-raid-disks 2
   nr-spare-disks 0
   device /dev/scsi/host0/bus0/target0/lun0/part2
   raid-disk 0
   device /dev/scsi/host0/bus0/target1/lun0/part2
   raid-disk 1


I was not able to boot from an LVM 2 since lilo does not grok 
device-mapper devices, btw lilo seems to need HDIO_GETGEO
syscall that is (was?) not available with device-mapper.

L.

P.S. in case yoo wonder sd?1 is the server diagnostic partition

-- 
Luca Berra -- bluca@comedia.it
	Service Delivery Manager
	Communication Media & Services S.r.l.
	Via A. Modigliani 1 - MILANO

[linux-lvm] raid1+lvm

[galt]

I got it working, thanks to all, especially to Luca. After verifying
that my lilo configuration was sane, I tried making the initrd on another
host. I was able to boot just fine.  I was trying to do everything from
the slackware 8.1 install cd, but the lvmcreate_initrd script doesnt want
to work properly in that environment.

Heres the setup:

# lilo -V
LILO version 22.2

# cat /etc/lilo.conf
lba32
boot = /dev/sda
delay = 50
vga = ext

image = /boot/vmlinuz
root = /dev/rootvg/root
initrd = /boot/initrd-lvm-2.4.18-heh3.gz
label = linux1
read-only

# df
Filesystem           1k-blocks      Used Available Use% Mounted on
/dev/rootvg/root       2097084    719204   1377880  35% /
/dev/rootvg/var        6254396     40824   6213572   1% /var

# swapon -s
Filename                        Type            Size    Used    Priority
/dev/rootvg/swap                partition       524280  0       -1

# cat /proc/lvm/global
LVM driver LVM version 1.0.1-rc4(ish)(03/10/2001)

# fdisk -l

Disk /dev/sda: 255 heads, 63 sectors, 1106 cylinders
Units = cylinders of 16065 * 512 bytes

   Device Boot    Start       End    Blocks   Id  System
/dev/sda1             1      1106   8883913+  fd  Linux raid autodetect

Disk /dev/sdb: 255 heads, 63 sectors, 1106 cylinders
Units = cylinders of 16065 * 512 bytes

   Device Boot    Start       End    Blocks   Id  System
/dev/sdb1             1      1106   8883913+  fd  Linux raid autodetect

# cat /etc/raidtab
raiddev /dev/md0
        raid-level 1
        nr-raid-disks 2
        nr-spare-disks 0
        device /dev/sda1
        raid-disk 0
        device /dev/sdb1
        raid-disk 1
#

LVM rules.

galt