raid 5 question

raid 5 question

[Marcus Schommer]

hello,
is an existing raid5 array expandable in the way lvm is,
so that i can add a disk, repartition and expand the file system on it?

thanks in advance,
marcus

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Re: raid 5 question

[Jakob Østergaard]

On Fri, Apr 26, 2002 at 10:47:05AM +0200, Marcus Schommer wrote:
> hello,
> is an existing raid5 array expandable in the way lvm is,
> so that i can add a disk, repartition and expand the file system on it?

Well, yes and no.

raidreconf (http://unthought.net/raidreconf) will do what you are asking,
so that makes it a "yes".  But the conversion can take considerable time
(a full day or more is not unheard of) - since you should take a full
backup of your system anyway, maybe the fastest solution would be to
simply get the backup done, re-create the array, and restore.

If your system has a lot of memory, it is possible that raidreconf is
faster.

In any case, I would be interested in hearing your experiences if you
decide to try out raidreconf.


-- 
................................................................
:   jakob@unthought.net   : And I see the elder races,         :
:.........................: putrid forms of man                :
:   Jakob Østergaard      : See him rise and claim the earth,  :
:        OZ9ABN           : his downfall is at hand.           :
:.........................:............{Konkhra}...............:
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Re: raid 5 question

[bo]

Is this URL right?

 " http://unthought.net/raidreconf)"

I could nto access it???

Bo

----- Original Message -----
From: "Jakob Østergaard" <jakob@unthought.net>
To: "Marcus Schommer" <schommer@rdts.de>
Cc: <linux-raid@vger.kernel.org>
Sent: Sunday, April 28, 2002 7:13 PM
Subject: Re: raid 5 question


> On Fri, Apr 26, 2002 at 10:47:05AM +0200, Marcus Schommer wrote:
> > hello,
> > is an existing raid5 array expandable in the way lvm is,
> > so that i can add a disk, repartition and expand the file system on it?
>
> Well, yes and no.
>
> raidreconf (http://unthought.net/raidreconf) will do what you are asking,
> so that makes it a "yes".  But the conversion can take considerable time
> (a full day or more is not unheard of) - since you should take a full
> backup of your system anyway, maybe the fastest solution would be to
> simply get the backup done, re-create the array, and restore.
>
> If your system has a lot of memory, it is possible that raidreconf is
> faster.
>
> In any case, I would be interested in hearing your experiences if you
> decide to try out raidreconf.
>
>
> --
> ................................................................
> :   jakob@unthought.net   : And I see the elder races,         :
> :.........................: putrid forms of man                :
> :   Jakob Østergaard      : See him rise and claim the earth,  :
> :        OZ9ABN           : his downfall is at hand.           :
> :.........................:............{Konkhra}...............:
> -
> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>

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Re: raid 5 question

[Maurice Hilarius]

With regards to your message at 09:43 AM 4/29/02, bo. Where you stated:
>Is this URL right?
>
>  " http://unthought.net/raidreconf)"
>
>I could nto access it???

Delete the bracket!!

>http://unthought.net/raidreconf


I  just tried the above version of the URL and it works for me..


With our best regards,

Maurice W. Hilarius       Telephone: 01-780-456-9771
Hard Data Ltd.               FAX:       01-780-456-9772
11060 - 166 Avenue        mailto:maurice@harddata.com
Edmonton, AB, Canada      http://www.harddata.com/
    T5X 1Y3

Ask me about the UP1500 Alpha - Full systems from $3,500!

Re: raid 5 question

[Derek Vadala]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: TEXT/PLAIN; charset=X-UNKNOWN, Size: 913 bytes --]

On Mon, 29 Apr 2002, [iso-8859-1] Jakob Østergaard wrote:

> raidreconf (http://unthought.net/raidreconf) will do what you are asking,

Is that the official site and are you and/or Danny Cox still working on
the code? I noticed that the raidreconf bundled with the raidtools-1.0 in
skipjack is 0.1.2 and the one at unthought.net is 0.1.1-- but maybe that's
because someone else worked on it and didn't put their name in.

> In any case, I would be interested in hearing your experiences if you
> decide to try out raidreconf.

I've still got a bunch of comparison tests to run, but I'll post the
results here when I' m done.


---
Derek Vadala, derek@cynicism.com, http://www.cynicism.com/~derek

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RAID detection and activation w/o auto detection

[bo]

Hello,

How to detect and activate the RAID manually without 
"auto detection"(0xFD in partition type)?

I tried with "mdadm -R" or "mdadm -A", but it did not work.

Thanks in advance,

Bo

Re: RAID detection and activation w/o auto detection

[Neil Brown]

On Monday April 29, bo@sosnetwork.net wrote:
> Hello,
> 
> How to detect and activate the RAID manually without 
> "auto detection"(0xFD in partition type)?
> 
> I tried with "mdadm -R" or "mdadm -A", but it did not work.

echo '/dev/hd* /dev/sd*' > /etc/mdadm.conf
mdadm -Dsb >> /etc/mdadm.conf

# look at /etc/mdadm.conf and make sure that it looks ok.

# add  "mdadm -As" to an appropriate startup script.

Note that this won't work for assembling the root filesystem.
To do that, you either need an init-ramdisk which runs "mdadm -As", or
use kernel parameters to start the root device.e.g.

  append="root=/dev/md0 md=0,/dev/hda1,/dev/hdc1"

NeilBrown

Re: RAID detection and activation w/o auto detection

[Mr. James W. Laferriere]

	Hello Neil ,  An suggestion for -D function of mdadm
	please allow use of  '-c/--config='  ?

	I tried the suggestion below .  But I did not want to overwrite
	the /etc version of mdadm.conf , cause it works .  So I tried to
	use the -c option & mdadm replies with the below .  Tia ,  JimL

~# mdadm -V
mdadm - v0.8.2 - 11 April 2002

~# echo '/dev/hd* /dev/sd*' > ./mdadm.conf

~# mdadm -Dsb -c ./mdadm.conf >> ./mdadm.conf
mdadm: option c not valid in misc mode

~# mdadm -Dsb --config=./mdadm.conf >> ./mdadm.conf
mdadm: option c not valid in misc mode


On Tue, 30 Apr 2002, Neil Brown wrote:

> On Monday April 29, bo@sosnetwork.net wrote:
> > Hello,
> >
> > How to detect and activate the RAID manually without
> > "auto detection"(0xFD in partition type)?
> >
> > I tried with "mdadm -R" or "mdadm -A", but it did not work.
>
> echo '/dev/hd* /dev/sd*' > /etc/mdadm.conf
> mdadm -Dsb >> /etc/mdadm.conf
>
> # look at /etc/mdadm.conf and make sure that it looks ok.
>
> # add  "mdadm -As" to an appropriate startup script.
>
> Note that this won't work for assembling the root filesystem.
> To do that, you either need an init-ramdisk which runs "mdadm -As", or
> use kernel parameters to start the root device.e.g.
>
>   append="root=/dev/md0 md=0,/dev/hda1,/dev/hdc1"
>
> NeilBrown
> -
> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>

       +------------------------------------------------------------------+
       | James   W.   Laferriere | System    Techniques | Give me VMS     |
       | Network        Engineer |     P.O. Box 854     |  Give me Linux  |
       | babydr@baby-dragons.com | Coudersport PA 16915 |   only  on  AXP |
       +------------------------------------------------------------------+

Re: RAID detection and activation w/o auto detection

[Mr. James W. Laferriere]

	Hello Neil ,  OK mia culpa .  But I don't see what good the echo
	below does for us then ,  as in ...

~# more ./mdadm.conf
/dev/hd* /dev/sd*
ARRAY /dev/md0 level=raid5 num-devices=3 UUID=b285b144:ae0b561b:b5b55686:ed216a4c

	Without the DEVICE in front of '/dev/hd* /dev/sd*' they are
	meaningless .  Right ?  Tia ,  JimL

On Tue, 30 Apr 2002, Mr. James W. Laferriere wrote:
> 	Hello Neil ,  An suggestion for -D function of mdadm
> 	please allow use of  '-c/--config='  ?
> 	I tried the suggestion below .  But I did not want to overwrite
> 	the /etc version of mdadm.conf , cause it works .  So I tried to
> 	use the -c option & mdadm replies with the below .  Tia ,  JimL
> ~# mdadm -V
> mdadm - v0.8.2 - 11 April 2002
> ~# echo '/dev/hd* /dev/sd*' > ./mdadm.conf
> ~# mdadm -Dsb -c ./mdadm.conf >> ./mdadm.conf
> mdadm: option c not valid in misc mode
> ~# mdadm -Dsb --config=./mdadm.conf >> ./mdadm.conf
> mdadm: option c not valid in misc mode

> On Tue, 30 Apr 2002, Neil Brown wrote:
> > On Monday April 29, bo@sosnetwork.net wrote:
> > > Hello,
> > > How to detect and activate the RAID manually without
> > > "auto detection"(0xFD in partition type)?
> > > I tried with "mdadm -R" or "mdadm -A", but it did not work.
> >
> > echo '/dev/hd* /dev/sd*' > /etc/mdadm.conf
> > mdadm -Dsb >> /etc/mdadm.conf
> >
> > # look at /etc/mdadm.conf and make sure that it looks ok.
> >
> > # add  "mdadm -As" to an appropriate startup script.
> >
> > Note that this won't work for assembling the root filesystem.
> > To do that, you either need an init-ramdisk which runs "mdadm -As", or
> > use kernel parameters to start the root device.e.g.
> >
> >   append="root=/dev/md0 md=0,/dev/hda1,/dev/hdc1"
> >
> > NeilBrown

       +------------------------------------------------------------------+
       | James   W.   Laferriere | System    Techniques | Give me VMS     |
       | Network        Engineer |     P.O. Box 854     |  Give me Linux  |
       | babydr@baby-dragons.com | Coudersport PA 16915 |   only  on  AXP |
       +------------------------------------------------------------------+

Re: RAID detection and activation w/o auto detection

[Neil Brown]

On Tuesday April 30, babydr@baby-dragons.com wrote:
> 
> 	Hello Neil ,  OK mia culpa .  But I don't see what good the echo
> 	below does for us then ,  as in ...
> 
> ~# more ./mdadm.conf
> /dev/hd* /dev/sd*
> ARRAY /dev/md0 level=raid5 num-devices=3 UUID=b285b144:ae0b561b:b5b55686:ed216a4c
> 
> 	Without the DEVICE in front of '/dev/hd* /dev/sd*' they are
> 	meaningless .  Right ?  Tia ,  JimL

Yep.  My mistake.  It should have been:

   echo 'DEVICE /dev/hd* /dev/sd*' > /etc/mdadm.conf

As I think you realised, --config is pointless with -Dsb, as it
doesn't read the config file, it reads /proc/mdstat.
However --config would be meaningful with -Esb, and the next release
will allow it.

Thanks,

NeilBrown

Re: raid 5 question

[Jakob Østergaard]

On Mon, Apr 29, 2002 at 10:05:12AM -0700, Derek Vadala wrote:
> On Mon, 29 Apr 2002, [iso-8859-1] Jakob Østergaard wrote:
> 
> > raidreconf (http://unthought.net/raidreconf) will do what you are asking,
> 
> Is that the official site and are you and/or Danny Cox still working on
> the code? 

1) It is the official site
2) We're not working on the code  ;)

>I noticed that the raidreconf bundled with the raidtools-1.0 in
> skipjack is 0.1.2 and the one at unthought.net is 0.1.1-- but maybe that's
> because someone else worked on it and didn't put their name in.

That is interesting - too bad RedHat didn't care to ask me about the known
problems with the tool... Some of the known problems are easily fixable.

I guess their customers will tell them what happens when raidreconf encounters
a bad block  ;)    (trivial fix by the way)

> 
> > In any case, I would be interested in hearing your experiences if you
> > decide to try out raidreconf.
> 
> I've still got a bunch of comparison tests to run, but I'll post the
> results here when I' m done.

Great !  Thanks,

Oh, and just to let everyone know:  I'm hoping that someone is going to take
raidreconf and integrate it into LVM or EVMS - this is clearly the way that
things *should* be going, and it would be needed for hot-reconfiguration
anyway.  I can't do this myself, because I simply don't have the time.

As I see it - while raidreconf might be useful as it is today (I wrote it
because I needed it, and it has helped me a few times), the concept of having
to dismount, raidstop, reconfigure (for 20+ hours!), raidstart, ext2resize, and
remount, is dead.  It is simply not acceptable.  RAID reconfiguration *MUST* be
on-line, and it must be something that's just running in the background while
the server is ticking away doing whatever it is it is doing.

Knowing that I can't integrate it in the kernel as it should be (because of my
own time constraints), and knowing that the way the tool works today
(userspace, non on-line) is not acceptable, doesn't give me much of an
incentive to keep "working" on it.

Now I will try to push this to someone else, rather than feeling bad about not
doing anything about a potentially really useful tool myself.

Cheers,   :)

-- 
................................................................
:   jakob@unthought.net   : And I see the elder races,         :
:.........................: putrid forms of man                :
:   Jakob Østergaard      : See him rise and claim the earth,  :
:        OZ9ABN           : his downfall is at hand.           :
:.........................:............{Konkhra}...............:
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Re: raid 5 question

[Derek Vadala]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: TEXT/PLAIN; charset=X-UNKNOWN, Size: 1275 bytes --]

On Tue, 30 Apr 2002, [iso-8859-1] Jakob Østergaard wrote:

> >I noticed that the raidreconf bundled with the raidtools-1.0 in
> > skipjack is 0.1.2 and the one at unthought.net is 0.1.1-- but maybe that's
> > because someone else worked on it and didn't put their name in.
> 
> That is interesting - too bad RedHat didn't care to ask me about the known
> problems with the tool... Some of the known problems are easily fixable.

There are indeed differences, but they all appear to be trivial. Looks
like some stuff was moved from rrc_common.c and into raidreconf.c,
specifcally the progress indicator, command line error-checking and user
confirmation. Everything else appears to be simple compatibility changes
for parts of the raidtools that raidreconf relies on. For example,
md-int.h is now md_p.h and md_u.h.

I'm about half way through the tests I want to run, so I should have some
data on how longs are expected to take tomorrow. So far it hasn't been as
slow as I expected.

---
Derek Vadala, derek@cynicism.com, http://www.cynicism.com/~derek

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