Mailing List Archive

Explanation of 'strange bm_offset'
Hello,

Just curious: occasionally I see something like this when creating meta
data on a new volume:

strange bm_offset -128 (expected: -192)

Everything seems to work fine, but in case this could potentially cause
errors I'd like to know if anyone else knows.

Thanks,

Chris
Re: Explanation of 'strange bm_offset' [ In reply to ]
On Sat, Apr 21, 2012 at 04:51:02PM -0400, Chris Dickson wrote:
> Hello,
>
> Just curious: occasionally I see something like this when creating meta
> data on a new volume:
>
> strange bm_offset -128 (expected: -192)
>
> Everything seems to work fine, but in case this could potentially cause
> errors I'd like to know if anyone else knows.

(((2*1024*1024*1024 - (4*1024) - (64*512)) / 4096 / 8 / 512) + 7)/8*8 + 64

You likely had a previous lv (of size 1 GB) with internal meta data,
destroyed that at some point without wiping the drbd meta data area,
later created a new LV (of size 2GB), and drbd found the old stale meta
data block in the garbage on disk, which does not quite match the new lv size.


When decommissioning an LV+DRBD,
maybe you want to at least "drbdadm wipe-md" just before the lvremove.


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

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