On Tue, Feb 12, 2008 at 10:21:44PM -0800, Jonathan Loran wrote: > > Hi List, > > I'm wondering if one of you expert DTrace guru's can help me. I want to > write a DTrace script to print out a a histogram of how long IO requests > sit in the service queue. I can output the results with the quantize > method. I'm not sure which provider I should be using for this. Does > anyone know? I can easily adapt one of the DTrace Toolkit routines for > this, if I can find the provider. > > I'll also throw out the problem I'm trying to meter. We are using ZFS > on a large SAN array (4TB). The pool on this array serves up a lot of > users, (250 home file systems/directories) and also /usr/local and other > OTS software. It works fine most of the time, but then gets overloaded > during busy periods. I'm going to reconfigure the array to help with > this, but I sure would love to have some metrics to know how big a > difference my tweaks are making. Basically, the problem users > experience, when the load shoots up are huge latencies. An ls on a > non-cached directory, which usually is instantaneous, will take 20, 30, > 40 seconds or more. Then when the storage array catches up, things get > better. My clients are not happy campers. > > I know, I know, I should have gone with a JBOD setup, but it's too late > for that in this iteration of this server. We we set this up, I had the > gear already, and it's not in my budget to get new stuff right now. > > Thanks for any help anyone can offer.
I have faced similar problem (although not exactly the same) and was going to monitor disk queue with dtrace but couldn't find any docs/urls about it. Finally asked Chris Gerhard for help. He partially answered via his blog: http://blogs.sun.com/chrisg/entry/latency_bubble_in_your_io Maybe it helps you. Regards przemol -- http://przemol.blogspot.com/ ---------------------------------------------------------------------- Masz ostatnia szanse ! Sprawdz >>> http://link.interia.pl/f1d02 _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
