[DRBD-user] write performance issues

Mark Dokter dokter at icg.tugraz.at
Mon Jul 11 16:13:10 CEST 2011

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

On 07/10/2011 07:30 PM, Phil Stoneman wrote:
> Hi Mark


> I've seen a similar thing with small writes, and for me, using
> no-disk-barrier and no-disk-flushes solved the small write performance
> issue. Hope that helps! :-)

>From [1]:
"Unfortunately device mapper (LVM) might not support barriers. "

Although, cat /proc/drbd states
3: cs:Connected ro:Secondary/Primary ds:UpToDate/UpToDate C r----
    ns:0 nr:46983440 dw:46983440 dr:0 al:0 bm:2863 lo:0 pe:0 ua:0 ap:0
ep:1 wo:b oos:0

Furthermore, my 3ware RAID controllers do not have a BBU installed and I
read that it's not recommended to use no-disk-barriers  and
no-disk-flushes in this case. The servers are connected to a quite large
ups tough. Does that suffice?


> Phil


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