[DRBD-user] Apologies...wrong subject: should have been drbd performance issue..

Lars Ellenberg Lars.Ellenberg at linbit.com
Wed Jun 21 20:17:04 CEST 2006

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


/ 2006-06-21 10:47:52 -0700
\ Tim Johnson:
>  Hi guys,
> 
> We've got a bit of a problem at a customer site and I was wondering if
> anybody had any suggestions.  With drbd up and running on both the
> primary and backup, massive amounts of data were copied over to the
> relevant mount points on the primary.  Apparently this slowed the
> machine down so much (haven't yet been able to get from them if it was
> the CPU usage or memory) that users were getting kicked off.  When drbd
> was taken down on the backup, then everything was o.k.  They started
> with drbd version 0.7.13.  I perused the archives of this mailing list
> and found something which suggested that this was a problem fixed after
> 0.7.13, so they upgraded to 0.7.19 and are still having the problem.
> Parameters we've thought might be appropriate in the drbd.conf file are
> protocol (using protocol A: I'm sure this is fine), sndbuf-size
> (warnings using large values like 1M), max-buffers (this looks promising
> to me), max-epoch-size, and maybe rate.  I'm a bit nervous about
> changing anything, so does anybody have some good ideas?
> 
> Appropriate environmental information such as proc/drbd and system info
> is below:
> 
> Thanks,
> Tim

> Machine 1: (primary, I believe)
> Link speed: 10 MBps  (T1 line)
> 1 NIC 100 MB/s.

well.
what exactly now is your replication link network bandwidth between
those boxes?
if that is a 100 Megabit / second, that will max out the write
throughput of connected drbd at around 10 MegaByte per second.
if that is a 10 MBps line, that obviously goes even down to
one megabyte per second...

what write rates does your customer actually observe,
and what write rates would he like to see?

-- 
: Lars Ellenberg                                  Tel +43-1-8178292-0  :
: LINBIT Information Technologies GmbH            Fax +43-1-8178292-82 :
: Schoenbrunner Str. 244, A-1120 Vienna/Europe   http://www.linbit.com :
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