[DRBD-user] online shrinking errors / Centos5 drbd 8.3.1 from Testing

Lars Ellenberg lars.ellenberg at linbit.com
Fri Jun 5 11:01:05 CEST 2009

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


On Fri, Jun 05, 2009 at 10:22:07AM +0200, Rainer Traut wrote:
> Hi all,
> 
> sys: Centos 5.3, drbd 8.3.1 from Centos-Testing
> kmod-drbd83-8.3.1-4.el5.centos.x86_64
> 
> Steps I did:
> 
> unmount filesystem then
> # resize2fs -p /dev/drbd0 25G
> # drbdadm -- --size=25G resize r0
> # lvresize -l 801 -t -v /dev/mapper/VG00-LVsrv
> (800 extends are 25GB, 1 for metadata)
> 
> All these commands came back w/o error, but drbd was detached:
> 
> drbd0: drbd_bm_resize called with capacity == 52428800
> drbd0: resync bitmap: bits=6553600 words=102400
> drbd0: size = 25 GB (26214400 KB)
> drbd0: Writing the whole bitmap, size changed
> drbd0: 0 KB (0 bits) marked out-of-sync by on disk bit-map.
> kjournald starting.  Commit interval 5 seconds
> attempt to access beyond end of device
> dm-1: rw=17, want=116588476, limit=52494336
> drbd0: drbd_md_sync_page_io(,116588475s,WRITE) failed!
> drbd0: disk( UpToDate -> Failed )
> drbd0: Local IO failed. Detaching...
> drbd0: disk( Failed -> Diskless )
> drbd0: Notified peer that my disk is broken.
> EXT3 FS on drbd0, internal journal
> EXT3-fs: mounted filesystem with ordered data mode.
> drbd0: Should have called drbd_al_complete_io(, 0), but my Disk seems to 
> have failed :(

expected, even though not exactly intuitive.
just because you resize (shrink) the storage area of DRBD,
it does not re-locate its internal meta data.

internal meta data always lives in the last sectors of the device.
so your lvresize truncated the device, and drbd tried to access beyond
end of device.
IO error.
detach.

 :(


-- 
: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com

DRBD® and LINBIT® are registered trademarks of LINBIT, Austria.
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