On 31 March 2016 at 04:17, Eric Ren <z...@suse.com> wrote: > Hi, > >> How did you perform the testing? It really matters. If you write a file on >>> shared disk from one node, and read this file from another node, without, >>> or with very little interval, the writing IO speed could decrease by ~20 >>> times according my previous testing(just as a reference). It's a >>> extremely >>> bad situation for 2 nodes cluster, isn't? >>> >>> But it's incredible that in your case writing speed drop by >3000 times! >>> >> >> >> I simply used 'dd' to create a file with /dev/zero as a source. If there >> is >> a better way to do this I am all ears. >> > > Alright, you just did a local IO on ocfs2, then the performance shouldn't > be that bad. I guess the ocfs2 volume has been used over 60%? or seriously > fragmented? > Please give info with `df -h`, and super block with debugfs.ocfs2, and > also the exact `dd` command you performed. Additionally, perform `dd` on > each node. > > You know, ocfs2 is a shared disk fs. So 3 basic testing cases I can think > of are: > 1. only one node of cluster do IO; > 2. more than one nodes of cluster perform IO, but each nodes just > read/write its own file on shared disk; > 3. like 2), but some nodes read and some write a same file on shared disk. > > The above model is much theoretically simplified though. The practical > scenarios could be much more complicated, like fragmentation issue that > your case much likely is.
Here is all the output requested: http://pastebin.com/raw/BnJAQv9T It's interesting to me that you guessed the usage is over 60%. It is indeed sitting at 65%. Is the solution as simple as ensuring that an OCFS2 filesystem doesn't go over the 60% usage mark? Or am I getting ahead of myself a little? Thanks for your effort so far! Graeme.
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