[linux-lvm] LVM / File descriptor .. left open / Snapshot-Problems

[Dr. Jürgen Vollmer]

Am Samstag, 23. Juli 2005 17:20 schrieb Alasdair G Kergon:
> On Sat, Jul 23, 2005 at 04:44:22PM +0200, Dr. Jürgen Vollmer wrote:
> > This is reproducable.
> > If I wait long enough (some 10 minutes) everything seems to work again.
>
> Add one or more -v options to the lvm commands to see more details.

The majer difference has been between a success and a failure has been:
  >   LV VGhome/lvm-snapshot in use: not removing
  >   Couldn't deactivate new snapshot.

> Run 'dmsetup info -c' and 'ls -l /sys/block/dm*' between lvm commands
> to check the changes have taken place.

after a non-successful lvcreate I get:
> dmsetup info -c
Name             Maj Min Stat Open Targ Event  UUID
VGhome-lvm--snapshot 253   1 L--w    0    1      0   
5mUudIrDe2N4x6x1D2T969Ux32kgljxXgbwKmGxoDE0SVIduDE3fboFFrMLFTqRB
VGhome-LVhome    253   0 L--w    2    5      0 
5mUudIrDe2N4x6x1D2T969Ux32kgljxX00000000000000000000000000000000


After a successfull lvcreate I get:
> dmsetup info -c
Name             Maj Min Stat Open Targ Event  UUID
VGhome-lvm--snapshot-cow 253   1 L--w    1    1      0 
5mUudIrDe2N4x6x1D2T969Ux32kgljxXAn7i5UocqOGzPhK0p9gT7zRjxJK1Nacn-cow
VGhome-lvm--snapshot 253   3 L--w    2    1      0 
5mUudIrDe2N4x6x1D2T969Ux32kgljxXAn7i5UocqOGzPhK0p9gT7zRjxJK1Nacn
VGhome-LVhome    253   0 L--w    2    1      0 
5mUudIrDe2N4x6x1D2T969Ux32kgljxX00000000000000000000000000000000
VGhome-LVhome-real 253   2 L--w    2    5      0 
5mUudIrDe2N4x6x1D2T969Ux32kgljxX00000000000000000000000000000000-real

but I have no glue what this means :-(

> Is there much or any I/O happening on the snapshotted device while you do
> this? 
no.
> Does adding 'sync' in between commands make any difference? 
no

I observed the following:
Initially I used "--extents 754"  approx. 2.9GB. If I reduce the size to 512M 
or less, lvcreate is always successful. For any value greater than 512M, the 
behaviour is as described.

With best regards
Jürgen


PS: My physcial setting is:
> pvdisplay
File descriptor 10 left open
File descriptor 11 left open
  --- Physical volume ---
  PV Name               /dev/sdb2
  VG Name               VGhome
  PV Size               16,08 GB / not usable 0
  Allocatable           yes (but full)
  PE Size (KByte)       4096
  Total PE              4117
  Free PE               0
  Allocated PE          4117
  PV UUID               qYRKMw-gcHH-MU12-qzMm-7Kpp-m0wD-bxYB9Q

  --- Physical volume ---
  PV Name               /dev/sdc2
  VG Name               VGhome
  PV Size               33,17 GB / not usable 0
  Allocatable           yes (but full)
  PE Size (KByte)       4096
  Total PE              8492
  Free PE               0
  Allocated PE          8492
  PV UUID               znM82W-cSIj-e0jR-CN4A-n1vZ-rdsm-a3uKfd

 --- Physical volume ---
  PV Name               /dev/sdd1
  VG Name               VGhome
  PV Size               68,49 GB / not usable 0
  Allocatable           yes
  PE Size (KByte)       4096
  Total PE              17533
  Free PE               754
  Allocated PE          16779
  PV UUID               UDiW4I-BXof-tKiE-QCTX-6pcW-iHZn-oxsT4U


all disks are SCSI disks (Ultra wide)

-- 
Dr.rer.nat. Juergen Vollmer, Viktoriastrasse 15, D-76133 Karlsruhe
Tel: +49(721) 9204871 Fax: +49(721) 24874
Juergen.Vollmer at informatik-vollmer.de
www.informatik-vollmer.de
Internet-Telefonie: www.skype.com Benutzer: juergen.vollmer
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