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[linux-lvm] Re: linux-lvm Digest, Vol 22, Issue 5



hi
 
i am totally new to the field of system programming...........
i wanna know about the device mapper  per se ...........
 
can anyone guide me how to approach the task...........
 
pls reply
Neelima

 
On 12/7/05, linux-lvm-request redhat com <linux-lvm-request redhat com > wrote:
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Today's Topics:

  1. Re: Which size for snapshot volume for a *safe* backup?
     (Alasdair G Kergon)
  2. Re: Which size for snapshot volume for a *safe* backup?
     (Alasdair G Kergon)
  3. Re: Dumb LVM question (Heinz Mauelshagen)
  4. Re: Which size for snapshot volume for a *safe* backup?
     (Marc-Jano Knopp)
  5. invalid lv in extent map (Greg Freemyer)
  6. LVM problems (Kelly Harding)
  7. Re: invalid lv in extent map (Greg Freemyer)
  8. Re: LVM problems (Kelly Harding)
  9. Re: LVM problems (Anil Kumar Sharma)


----------------------------------------------------------------------

Message: 1
Date: Tue, 6 Dec 2005 01:03:58 +0000
From: Alasdair G Kergon <agk redhat com >
Subject: Re: [linux-lvm] Which size for snapshot volume for a *safe*
       backup?
To: LVM general discussion and development <linux-lvm redhat com>
Message-ID: < 20051206010357 GF3647 agk surrey redhat com>
Content-Type: text/plain; charset=us-ascii

On Mon, Dec 05, 2005 at 11:39:11PM +0100, Marc-Jano Knopp wrote:
>   But for files smaller than that (like 512 bytes), it erronously
>   prints:
>
>     Device /dev/loop/0 not found

Maybe should be changed to:
Device /dev/loop/0 not found (or ignored by filters).

Tiny devices are filtered out at a low level in the code as
it is never valid for lvm2 to scan them to see if they
are PVs.

This was added for devices with extended partitions.
# blockdev --getsize /dev/hda4
2

Alasdair
--
agk redhat com



------------------------------

Message: 2
Date: Tue, 6 Dec 2005 01:10:17 +0000
From: Alasdair G Kergon < agk redhat com>
Subject: Re: [linux-lvm] Which size for snapshot volume for a *safe*
       backup?
To: LVM general discussion and development <linux-lvm redhat com >
Message-ID: <20051206011017 GG3647 agk surrey redhat com>
Content-Type: text/plain; charset=us-ascii

On Mon, Dec 05, 2005 at 11:39:11PM +0100, Marc-Jano Knopp wrote:
> So, obviously,
>   snapshot volume size = original volume size
> is not sufficient to hold a complete change of the original volume.

Correct - there's a little bit of metadata required too to
map each piece of data back into the right location.

> Btw.: There's a bug in "lvscan", it still displayed the snapshot
> as being "ACTIVE", while in fact (at least that's what I concluded),
> it was "INACTIVE" due to the lack of space, as shown using "lvdisplay".

The 'lvs' attributes should be accurate (and lvdisplay too I think).
lvscan doesn't check properly and needs fixing, thanks.

Alasdair
--
agk redhat com



------------------------------

Message: 3
Date: Tue, 6 Dec 2005 11:56:00 +0100
From: Heinz Mauelshagen < mauelshagen redhat com>
Subject: Re: [linux-lvm] Dumb LVM question
To: LVM general discussion and development <linux-lvm redhat com>
Cc: hjm redhat com
Message-ID: <20051206105600 GB2778 redhat com>
Content-Type: text/plain; charset=us-ascii

On Mon, Dec 05, 2005 at 01:29:23PM -0500, Greg Freemyer wrote:
> All,
>
> With LVM 2, how do I kill any and all snapshots.
>
> With LVM 1 it was "vgscan -r".
>
> I need to be able to do this with a script, so I'm hoping lvm 2 has a
> way to kill all snapshots without knowing their names, etc.  If not, I
> guess I can script up something to do the job.

Yes, you could use something like:

<quick_hacking_mode>
lvs|perl -ne '@a = split /\s+/,$_;if ($a[3] =~ /^s/) {print "/dev/$a[2]/$a[1]\n";}'|xargs lvremove -f
</quick_hacking_mode>


>
> Greg
> --
> Greg Freemyer
> The Norcross Group
> Forensics for the 21st Century
>
>
> --
> Greg Freemyer
> The Norcross Group
> Forensics for the 21st Century
>
> _______________________________________________
> 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/

--

Regards,
Heinz    -- The LVM Guy --

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

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

Heinz Mauelshagen                                 Red Hat GmbH
Consulting Development Engineer                   Am Sonnenhang 11
Cluster and Storage Development                   56242 Marienrachdorf
                                                 Germany
Mauelshagen RedHat com                            +49 2626 141200
                                                      FAX 924446
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-



------------------------------

Message: 4
Date: Tue, 6 Dec 2005 12:36:29 +0100
From: Marc-Jano Knopp <pub_ml_lvm marc-jano de>
Subject: Re: [linux-lvm] Which size for snapshot volume for a *safe*
       backup?
To: LVM general discussion and development <linux-lvm redhat com>
Message-ID: <20051206113629 GB2867 mjk myfqdn de >
Content-Type: text/plain; charset=us-ascii

On Tue, 06 Dec 2005 at 01:10 (+0000), Alasdair G Kergon wrote:
> On Mon, Dec 05, 2005 at 11:39:11PM +0100, Marc-Jano Knopp wrote:
> > So, obviously,
> >   snapshot volume size = original volume size
> > is not sufficient to hold a complete change of the original volume.
>
> Correct - there's a little bit of metadata required too to
> map each piece of data back into the right location.

Thought so, just wasn't sure if it gets stored inside the volume or in
an extra file or device.


I have noticed that lvdisplay <snapshot volume> prints:

Allocated to snapshot:   5.00%

But as I don't know the inner workings of LVM, I preferred not to take
this value for all variants of logical volumes for granted, but instead
ask here in this list for exact numbers.


[lvscan displays inactive snapshot volume as active]

> The 'lvs' attributes should be accurate (and lvdisplay too I think).
> lvscan doesn't check properly and needs fixing, thanks.

http://www.gotfuturama.com/Multimedia/EpisodeSounds/2ACV14/10.mp3

:-)


Best regards

Marc-Jano



------------------------------

Message: 5
Date: Tue, 6 Dec 2005 17:40:36 -0500
From: Greg Freemyer <greg freemyer gmail com>
Subject: [linux-lvm] invalid lv in extent map
To: LVM general discussion and development < linux-lvm redhat com>
Message-ID:
       <87f94c370512061440s6b1b7ca0rffad7f53503309e4 mail gmail com>
Content-Type: text/plain; charset=ISO-8859-1

I have recently upgraded a test server from 2.4.x with LVM 1 to 2.6.13
with LVM 2.

I can mount my 3 LVs, but when I try to do basic lvm commands I get
"invalid lv in extent map".

# pvscan
invalid lv in extent map
Couldn't fill logical volume maps.
invalid lv in extent map
Couldn't fill logical volume maps.
No matching physical volumes found

# pvscan --version
LVM version:     2.01.14 (2005-08-04)
Library version: 1.01.04 (2005-08-02)
Driver version:  4.4.0

I did not run vgconvert manually, so I assume I still have LVM1 metadata.

This is a test server, so none of the data in the LVs is important,
but I hope to be upgrading my live file server soon, so I would like
to figure out how to not lose any data.

Thanks
Greg
--
Greg Freemyer
The Norcross Group
Forensics for the 21st Century



------------------------------

Message: 6
Date: Wed, 07 Dec 2005 01:47:49 +0000
From: Kelly Harding <kelly harding ntlworld com>
Subject: [linux-lvm] LVM problems
To: linux-lvm redhat com
Message-ID: <43963F45 5060104 ntlworld com>
Content-Type: text/plain; charset="iso-8859-1"

Hi,

I've just brought my Debian Linux box back up after a power failure and
now my LVM set up seems to be non-functional.

I'm not very clued up on LVM tbh, but it has worked so far fine for ages.

I get the following error if I try  to run 'vgchange -a y 3diskvolume:

device-mapper ioctl cmd 11 failed: Invalid argument
  _deps: task run failed for (254:0)
  Failed to add device (254:0) to dtree
  1 logical volume(s) in volume group "3diskvolume" now active

It obviously won't mount after that as mount tells me it can't find the
superblock etc.

any ideas? is one of the discs dead?

Thanks,

Kelly
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Message: 7
Date: Tue, 6 Dec 2005 20:52:21 -0500
From: Greg Freemyer <greg freemyer gmail com>
Subject: [linux-lvm] Re: invalid lv in extent map
To: LVM general discussion and development <linux-lvm redhat com>
Message-ID:
       < 87f94c370512061752g3d948e01t15b17902a130da63 mail gmail com>
Content-Type: text/plain; charset=ISO-8859-1

Not sure how I caused the below, but after a reboot I was unable to
use my VG at all.

I wiped it out and rebuilt it.  Hopefully it does not happen again.

Greg

On 12/6/05, Greg Freemyer <greg freemyer gmail com> wrote:
> I have recently upgraded a test server from 2.4.x with LVM 1 to 2.6.13
> with LVM 2.
>
> I can mount my 3 LVs, but when I try to do basic lvm commands I get
> "invalid lv in extent map".
>
> # pvscan
>   invalid lv in extent map
>   Couldn't fill logical volume maps.
>   invalid lv in extent map
>   Couldn't fill logical volume maps.
>   No matching physical volumes found
>
> # pvscan --version
>   LVM version:     2.01.14 (2005-08-04)
>   Library version: 1.01.04 (2005-08-02)
>   Driver version:  4.4.0
>
> I did not run vgconvert manually, so I assume I still have LVM1 metadata.
>
> This is a test server, so none of the data in the LVs is important,
> but I hope to be upgrading my live file server soon, so I would like
> to figure out how to not lose any data.
>
> Thanks
> Greg
> --
> Greg Freemyer
> The Norcross Group
> Forensics for the 21st Century
>


--
Greg Freemyer
The Norcross Group
Forensics for the 21st Century



------------------------------

Message: 8
Date: Wed, 07 Dec 2005 02:06:18 +0000
From: Kelly Harding <kelly harding ntlworld com>
Subject: Re: [linux-lvm] LVM problems
To: kelly harding ntlworld com , LVM general discussion and development
       <linux-lvm redhat com>
Message-ID: <4396439A 7080500 ntlworld com >
Content-Type: text/plain; charset="iso-8859-1"

Hi again,

Forgot to add details:

PC: dual PII/350mhz (p/pro overdrive), 512mb ram, SCSI LVD 80mb/s.

The VG is across 3 36gb scsi drives attached to an adaptect 2940U2W card.

I'm running kernel version 2.4.27 (2.6 doesn't seem to like this system).

I noticed from the dmesg output the following:

device-mapper: one of name or uuid must be supplied, cmd(11)

This appears when the previously mentioned command is run.

I've no idea what this means or if it isa case of a re-install of the
base system might fix this? maybe something with the
base system has gone a bit fubar?

any help or advice on this would be greatly appreciated.

If it comes ot it that I lose the data and have to format and star the
LVM VG over again it won't be ideal but it won't
be losing anything vital either (just video files, etc).

Kelly
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------------------------------

Message: 9
Date: Wed, 7 Dec 2005 13:36:57 +0530
From: Anil Kumar Sharma < xplusaks gmail com>
Subject: Re: [linux-lvm] LVM problems
To: kelly harding ntlworld com, LVM general discussion and development
       <linux-lvm redhat com>
Message-ID:
       <52fe6b680512070006i7578827av304946cd51d37313 mail gmail com >
Content-Type: text/plain; charset="iso-8859-1"

Recently I also suffered problems with LVM(2)

These are very basic things I presume U might have already done but just in
case if not ...

imho pl boot with rescue disk (or mode)
As a precaution select read-only mount of file system
if required chroot to /mnt/sysimage
# mount  ! look for lvm things specifically a word - mapper
# pvdisplay
# vgdisplay
# lvdisplay
# pvscan
# vgscan
# lvscan

thiese will tell status of lvm things
Then check /etc/fstab (carefully)

U may then "very very carefully" use e2fsck or fsck [{("after dismounting
the volumes")}] as you may you deem fit.
"very very carefully"  means, as a minimum, first read both manpages, try
these commands in read-only mode + do not modify anything + verbose.

### use vgck with caution and also checkout /etc/lvm/lvm.conf

U may try in init 1 mode also but more caution requested.

good luck & Pl post if U get it right this way or anyway.

--
Anil Kumar Shrama
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