Date: Fri, 25 Jan 2013 11:29:14 +0200 From: Marin Atanasov Nikolov <dnaeon@gmail.com> To: John <john@theusgroup.com> Cc: ml-freebsd-stable <freebsd-stable@freebsd.org> Subject: Re: Spontaneous reboots on Intel i5 and FreeBSD 9.0 Message-ID: <CAJ-UWtT8pFn86OMpPG47ryKN%2B%2B=1KfaQX3JtbCLuu_kByvtMzA@mail.gmail.com> In-Reply-To: <CAJ-UWtR%2Bymv_%2BxpLcw01r9r=ym6gMh%2BHt4KfTabWQXXcAv5Ydw@mail.gmail.com> References: <CAJ-UWtSANRMsOqwW9rJ6Eebta6=AiHeNO6fhPO0mhYhZiMmn4A@mail.gmail.com> <op.wq3zxn038527sy@ronaldradial.versatec.local> <alpine.BSF.2.00.1301180758460.96418@wonkity.com> <1358527685.32417.237.camel@revolution.hippie.lan> <20130118173602.GA76438@neutralgood.org> <alpine.BSF.2.00.1301181313560.1604@wonkity.com> <CAJ-UWtRRfCKg9GBR_ppvtjvJGadiOXMXBFBpX7tAvLEXDoZHQg@mail.gmail.com> <20130119201914.84B761CB@server.theusgroup.com> <CAJ-UWtR%2Bymv_%2BxpLcw01r9r=ym6gMh%2BHt4KfTabWQXXcAv5Ydw@mail.gmail.com>
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Hello again :) Here's my update on these spontaneous reboots after less than a week since I've updated to stable/9. First two days the system was running fine with no reboots happening, so I though that this update actually fixed it, but I was wrong. The reboots are still happening and still no clear evidence of the root cause. What I did so far: * Ran disks tests -- looking good * Ran memtest -- looking good * Replaced power cables * Ran UPS tests -- looking good * Checked for any bad capacitors -- none found * Removed all ZFS snapshots There is also one more machine connected to the same UPS, so if it was a UPS issue I'd expect that the other one reboots too, but that's not the case. Now that I've excluded the hardware part of this problem I started looking again into the software side, and this time in particular -- ZFS. I'm running FreeBSD 9.1-STABLE #1 r245686 on a Intel i5 with 8Gb of memory. A quick look at top(1) showed lots of memory usage by ARC and my available free memory dropping fast. I've made a screenshot, which you can see on the link below: * http://users.unix-heaven.org/~dnaeon/top-zfs-arc.jpg So I went to the FreeBSD Wiki and started reading the ZFS Tuning Guide [1], but honestly at the end I was not sure which parameters I need to increase/decrease and to what values. Here's some info about my current parameters. % sysctl vm.kmem_size_max vm.kmem_size_max: 329853485875 % sysctl vm.kmem_size vm.kmem_size: 8279539712 % sysctl vfs.zfs.arc_max vfs.zfs.arc_max: 7205797888 % sysctl kern.maxvnodes kern.maxvnodes: 206227 There's one script at the ZFSTuningGuide which calculates kernel memory utilization, and for me these values are listed below: TEXT=22402749, 21.3649 MB DATA=4896264192, 4669.44 MB TOTAL=4918666941, 4690.81 MB While looking for ZFS tuning I've also stumbled upon this thread in the FreeBSD Forums [2], where the OP describes a similar behaviour to what I am already experiencing, so I'm quite worried now that the reason for these crashes is ZFS. Before jumping into any change to the kernel parameters (vm.kmem_size, vm.kmem_max_size, kern.maxvnodes, vfs.zfs.arc_max) I'd like to hear any feedback from people that have already done such optimizations on their ZFS systems. Could you please share what are the optimal values for these parameters on a system with 8Gb of memory? Is there a way to calculate these values or is it just a "test-and-see-which-fits-better" way of doing this? Thanks and regards, Marin [1]: https://wiki.freebsd.org/ZFSTuningGuide [2]: http://forums.freebsd.org/showthread.php?t=9143 On Sun, Jan 20, 2013 at 3:44 PM, Marin Atanasov Nikolov <dnaeon@gmail.com>wrote: > > > > On Sat, Jan 19, 2013 at 10:19 PM, John <john@theusgroup.com> wrote: > >> >At 03:00am I can see that periodic(8) runs, but I don't see what could >> have >> >taken so much of the free memory. I'm also running this system on ZFS and >> >have daily rotating ZFS snapshots created - currently the number of ZFS >> >snapshots are > 1000, and not sure if that could be causing this. Here's >> a >> >list of the periodic(8) daily scripts that run at 03:00am time. >> > >> >% ls -1 /etc/periodic/daily >> >800.scrub-zfs >> > >> >% ls -1 /usr/local/etc/periodic/daily >> >402.zfSnap >> >403.zfSnap_delete >> >> On a couple of my zfs machines, I've found running a scrub along with >> other >> high file system users to be a problem. I therefore run scrub from cron >> and >> schedule it so it doesn't overlap with periodic. >> >> I also found on a machine with an i3 and 4G ram that overlapping scrubs >> and >> snapshot destroy would cause the machine to grind to the point of being >> non-responsive. This was not a problem when the machine was new, but >> became one >> as the pool got larger (dedup is off and the pool is at 45% capacity). >> >> I use my own zfs management script and it prevents snapshot destroys from >> overlapping scrubs, and with a lockfile it prevents a new destroy from >> being >> initiated when an old one is still running. >> >> zfSnap has its -S switch to prevent actions during a scrub which you >> should >> use if you haven't already. >> >> > Hi John, > > Thanks for the hints. It was a long time since I've setup zfSnap and I've > just checked the configuration and I am using the "-s -S" flags, so there > should be no overlapping. > > Meanwhile I've updated to 9.1-RELEASE, but then I hit an issue when trying > to reboot the system (which appears to be discussed a lot in a separate > thread). > > Then I've updated to stable/9, so at the least the reboot issue is now > solved. Since I've to stable/9 I'm monitoring the system's memory usage and > so far it's been pretty stable, so I'll keep an eye of an update to > stable/9 has actually fixed this strange issue. > > Thanks again, > Marin > > >> Since making these changes, a machine that would have to be rebooted >> several >> times a week has now been up 61 days. >> >> John Theus >> TheUs Group >> > > > > -- > Marin Atanasov Nikolov > > dnaeon AT gmail DOT com > http://www.unix-heaven.org/ > -- Marin Atanasov Nikolov dnaeon AT gmail DOT com http://www.unix-heaven.org/
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