[DRBD-user] Concurrent writes

Gennadiy Nerubayev parakie at gmail.com
Tue Apr 21 23:18:19 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 Tue, Apr 21, 2009 at 2:47 PM, Roof, Morey R. <MRoof at admin.nmt.edu> wrote:

> This is a really interesting discussion.  I use DRBD to replicate
> volumes that are exported via blockio with IET and have never gotten
> this message.  I currently use DRBD 8.0.16 and over the last year with
> 8.0.x series this message has never appeared.  Before deployment all
> sorts of io tests were conducted and this message wasn't present then
> either.


Thanks for the input. What are the initiators that you're using?

So, I have an idea of a setting for you to change on your iSCSI target
> system and I'm really curious if the message goes away.  In IET we have
> "InitialR2T Yes" but the default is "No".  Trying running that way and
> see what happens as I'm very curious about the results.
>

Just tried "InitialR2T Yes", and there was no effect; the concurrent write
warnings are still being generated.

As a side note for anyone who would like to test this, on windows in
particular, here's one of tools I use to duplicate this:

SQLIO:
http://www.microsoft.com/downloads/details.aspx?familyid=9a8b005b-84e4-4f24-8d65-cb53442d9e19&displaylang=en
Contents of param.txt (this assumes f: is the remote storage, and you have
one gb free space available): f:\testfile.dat 4 0x0 1024
Command to run: sqlio -kW -s60 -frandom -o8 -b8 -LS -Fparam.txt

-Gennadiy
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