Red Hat Bugzilla – Bug 252384
cmirror resync slows down when I/O is outstanding to the mirror
Last modified: 2013-09-23 11:31:26 EDT
Cloning off the piece about performance of mirror resync dropping. +++ This bug was initially created as a clone of Bug #252007 +++ Description of problem: -- Additional comment from nstraz@redhat.com on 2007-08-13 15:40 EST -- We've run into similar problems with a fresh syncing mirror. When we do a mkfs on a not-yet-synced mirror, the mirror sync performance drops. I did a quick test now and found that on a 100G mirror with 3 legs (lvcreate -m 2), sync performance was about 0.9% completion per minute. After starting a mkfs -t gfs (which hangs) mirror completion drops to 0.05% per minute. -- Additional comment from jbrassow@redhat.com on 2007-08-13 15:46 EST -- Cluster mirrors in 4.5 did not have a way to coordinate device resyncing and nominal I/O. Therefore, nominal I/O had to be deferred until the regions were resync'ed - causing excessive delay. This has been addressed in 4.6. See bug 238629.
The latest build in 4.6 (>= 9/28/07). Addresses some of these concerns. I was forced to trade consistency for speed, however. So, things will be faster than 4.5, but I'd like to know what the limitations are. assigned -> needinfo
needinfo -> assigned I have a patch ready, but it still needs to be tested. I borrowed some ideas from the rhel5 code, which I am using to limit the network traffic while there is recovery + nominal I/O happening. Perhaps this patch could make 4.8.
The Red Hat Cluster Suite product is past end-of-life; closing.