Date: Wed, 27 Jun 2012 20:02:17 +0300 From: Levent Serinol <lserinol@gmail.com> To: Andreas Nilsson <andrnils@gmail.com> Cc: "freebsd-fs@freebsd.org" <freebsd-fs@freebsd.org> Subject: Re: ZFS stalls on Heavy I/O Message-ID: <DD521FBB-CFAD-4D51-8D0A-D21240FB30FE@gmail.com> In-Reply-To: <CAPS9%2BSs1oCh=Szhf_qCam85hPh%2BMFu-XRjTEJZT5hYt12qMhXw@mail.gmail.com> References: <CACqg54Si-vHFAVkjpTS40MZt4E1Kn14kDUFKmVb8vx449fCnFw@mail.gmail.com> <CAMXYB4K%2B9EKPyqdCRZZgLvDQuwK=AAGSZi8%2B-AfkOrnJQzwdUA@mail.gmail.com> <CAPS9%2BSs1oCh=Szhf_qCam85hPh%2BMFu-XRjTEJZT5hYt12qMhXw@mail.gmail.com>
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Hi, On 27 Haz 2012, at 19:34, Andreas Nilsson <andrnils@gmail.com> wrote: >=20 >=20 > On Wed, Jun 27, 2012 at 5:50 PM, Dean Jones <dean.jones@oregonstate.edu> w= rote: > On Wed, Jun 27, 2012 at 2:15 AM, Levent Serinol <lserinol@gmail.com> wrote= : > > Hi, > > > > Under heavy I/O load we face freeze problems on ZFS volumes on both > > Freebsd 9 Release and 10 Current versions. Machines are HP servers (64bi= t) > > with HP Smart array 6400 raid controllers (with battery units). Every da= > > device is a hardware raid5 where each one includes 9x300GB 10K SCSI hard= > > drivers. Main of I/O pattern happens on local system except some small N= FS > > I/O from some other servers (NFS lookup/getattr/ etc.). These servers ar= e > > mail servers (qmail) with small I/O patterns (64K Read/Write). Below yo= u > > can find procstat output on freeze time. write_limit is set to 200MB > > because of the huge amount of txg_wait_opens observed before. Every proc= ess > > stops on D state I think due to txg queue and other 2 queues are full. I= s > > there any suggestion to fix the problem ? > > > > btw inject_compress is the main process injecting emails to user inboxes= > > (databases). Also, those machines were running without problems on > > Linux/XFS filesystem. For a while ago, we started migration from Linux t= o > > Freebsd > > > > > > http://pastebin.com/raw.php?i=3Dic3YepWQ > > _______________________________________________ >=20 > Looks like you are running dedup with only 12 gigs of ram? >=20 > Dedup is very ram hungry and the dedup tables are probably no longer > fitting entirely in memory and therefore the system is swapping and > thrashing about during writes. >=20 > Also ZFS really prefers to directly address drives instead of RAID > controllers. It can not guarantee or know what the controller is > doing behind the scenes. > You might want to read http://constantin.glez.de/blog/2011/07/zfs-dedupe-o= r-not-dedupe and see if you need more ram. >=20 > And yes, having raid below zfs somewhat defeats the point of zfs. >=20 > Regards > Andreas That was one the machines, i'm running several similar machines except few c= hanges. For examplw some of them have 50gb and 20gbs of ram and some of them= has direct access every disk itself on poil as you suggested ( pools includ= ing 24 disks) some of the machines also running p812 hp raid cards (1gb cach= e ) , every hp card has battery unit. Every machine wheter rumning on 50gb r= am or pools with lots of disks have the same stall problem except one of the= m which is using hp p6300 san with fc connection . It's running zfs without p= roblems. Do i have to suspect on ciss driver which is common on all machines= where problems occur ? Wheter they use 6400 or p812 raid cards all of them = is using same ciss driver except the one connected via fc to san. Btw when zfs stalls after 1-2 minutes later it contiunes to write and read a= s usual.=20 Do you suspect any problem in procstat ouput that i provided ? Thanks, Levent=
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