[DRBD-user] Problems after upgrade 8.2.0 to 8.3.0

Lars Ellenberg lars.ellenberg at linbit.com
Mon Feb 9 20:08:01 CET 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 Mon, Feb 09, 2009 at 07:18:46PM +0100, Matteo Tescione wrote:
> It's a long time since i've been using the no-disk-barrier, no-disk-flushes
> and no drain to optimize the performance of our datastores (3ware 9650 w/
> BBU cache) but it has no apparent correlations btw the 2 mentioned drbd
> version (8.2.7 vs 8.3.0)
> 
> We are using Centos5.2 x86_64 with a custom kernel and the read performance
> lost (about 20%) is only seen running 8.3.0 (same config&setup)

works for me.

and, if its READ you have that problem on,
maybe you need to adjust your read ahead settings.

drbd does nothing funny on reads but just keeps a stub of housekeeping
information to be able to retry in case of read error, then passes it on
to the lower level device.

there is nothing I can see right now that would impact performance.

> If you don't believe me I can produce logs and iostats during some IO test.

I doubt that the "iostats" statistics would help here in any way.
but I may be wrong.
so yes, go ahead.

> In the btw, iostats accounting for drbd devices is still crazy, even
> reverting back to 8.2.7

can you be more specific?

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

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