Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
/ 2006-05-08 08:27:56 +0000 \ Torsten Neumann: > Francis I. Malolot <francis_m at ...> writes: > > > > > >>>When putting linux software raid5 on top it goes unusable slow > > > > Raid 5 slow performance is normal especially write because > > it must read overhead blocks in the stripe to recreate the parity block. > > > > Please look where is the bottleneck. > > disk write without drbd 40MB/sec > disk write with drbd (recent kernel) ~ 3MB/sec (gigabit link) > > So how can I check why drbd slows things so terrible down? Yes there is a > bottleneck. But without drbd all seems fine, with drbd not. see what io scheduler is in use (/sys/block/lower-level-device/queue/scheduler) on servers I prefer "deadline". you can switch to "deadline" like this: for q in /sys/block/*/queue/scheduler ; do echo deadline > "$q" done or by specifying a boot-time commandline parameter. if that did not help yet, check wether increasing "max-buffers" and/or decreasing "max-epoch-size" in drbd.conf does help. -- : 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 : __ please use the "List-Reply" function of your email client.