hi, With that much storage and that many snapshots, I do think you need more than 96GB of RAM in the box. I'm hoping someone doing active ZFS work can comment..
I don't think the ZFS code is completely "memory usage" safe. The "old" Sun suggestions when I started using ZFS was "if your server panics due to out of memory with ZFS, buy more memory." That said, there doesn't look like there's a leak anywhere - those dumps show you're using at least 32gig on each just in zfs data buffers. Try tuning the ARC down a little? -adrian On 13 July 2015 at 04:48, Christopher Forgeron <csforge...@gmail.com> wrote: > > > TL;DR Summary: I can run FreeBSD out of memory quite consistently, and it’s > not a TOS/mbuf exhaustion issue. It’s quite possible that ZFS is the > culprit, but shouldn’t the pager be able to handle aggressive memory > requests in a low memory situation gracefully, without needing custom tuning > of ZFS / VM? > > > Hello, > > I’ve been dealing with some instability in my 10.1-RELEASE and > STABLEr282701M machines for the last few months. > > These machines are NFS/iSCSI storage machines, running on Dell M610x or > similar hardware, 96 Gig Memory, 10Gig Network Cards, dual Xeon Processors – > Fairly beefy stuff. > > Initially I thought it was more issues with TOS / jumbo mbufs, as I had this > problem last year. I had thought that this was properly resolved, but > setting my MTU to 1500, and turning off TOS did give me a bit more > stability. Currently all my machines are set this way. > > Crashes were usually represented by loss of network connectivity, and the > ctld daemon scrolling messages across the screen at full speed about lost > connections. > > All of this did seem like more network stack problems, but with each crash > I’d be able to learn a bit more. > > Usually there was nothing of any use in the logfile, but every now and then > I’d get this: > > Jun 3 13:02:04 san0 kernel: WARNING: 172.16.0.97 > (iqn.1998-01.com.vmware:esx5a-3387a188): failed to allocate memory > Jun 3 13:02:04 san0 kernel: WARNING: icl_pdu_new: failed to allocate 80 > bytes > Jun 3 13:02:04 san0 kernel: WARNING: 172.16.0.97 > (iqn.1998-01.com.vmware:esx5a-3387a188): failed to allocate memory > Jun 3 13:02:04 san0 kernel: WARNING: icl_pdu_new: failed to allocate 80 > bytes > Jun 3 13:02:04 san0 kernel: WARNING: 172.16.0.97 > (iqn.1998-01.com.vmware:esx5a-3387a188): failed to allocate memory > --------- > Jun 4 03:03:09 san0 kernel: WARNING: icl_pdu_new: failed to allocate 80 > bytes > Jun 4 03:03:09 san0 kernel: WARNING: icl_pdu_new: failed to allocate 80 > bytes > Jun 4 03:03:09 san0 kernel: WARNING: 172.16.0.97 > (iqn.1998-01.com.vmware:esx5a-3387a188): failed to allocate memory > Jun 4 03:03:09 san0 kernel: WARNING: 172.16.0.97 > (iqn.1998-01.com.vmware:esx5a-3387a188): connection error; dropping > connection > Jun 4 03:03:09 san0 kernel: WARNING: 172.16.0.97 > (iqn.1998-01.com.vmware:esx5a-3387a188): connection error; dropping > connection > Jun 4 03:03:10 san0 kernel: WARNING: 172.16.0.97 > (iqn.1998-01.com.vmware:esx5a-3387a188): waiting for CTL to terminate tasks, > 1 remaining > Jun 4 06:04:27 san0 syslogd: kernel boot file is /boot/kernel/kernel > > So knowing that it seemed to be running out of memory, I started leaving > leaving ‘vmstat 5’ running on a console, to see what it was displaying > during the crash. > > It was always the same thing: > > 0 0 0 1520M 4408M 15 0 0 0 25 19 0 0 21962 1667 91390 > 0 33 67 > 0 0 0 1520M 4310M 9 0 0 0 2 15 3 0 21527 1385 95165 > 0 31 69 > 0 0 0 1520M 4254M 7 0 0 0 14 19 0 0 17664 1739 72873 > 0 18 82 > 0 0 0 1520M 4145M 2 0 0 0 0 19 0 0 23557 1447 96941 > 0 36 64 > 0 0 0 1520M 4013M 4 0 0 0 14 19 0 0 4288 490 34685 0 > 72 28 > 0 0 0 1520M 3885M 2 0 0 0 0 19 0 0 11141 1038 69242 > 0 52 48 > 0 0 0 1520M 3803M 10 0 0 0 14 19 0 0 24102 1834 91050 > 0 33 67 > 0 0 0 1520M 8192B 2 0 0 0 2 15 1 0 19037 1131 77470 > 0 45 55 > 0 0 0 1520M 8192B 0 22 0 0 2 0 6 0 146 82 578 0 > 0 100 > 0 0 0 1520M 8192B 1 0 0 0 0 0 0 0 130 40 510 0 > 0 100 > 0 0 0 1520M 8192B 0 0 0 0 0 0 0 0 143 40 501 0 > 0 100 > 0 0 0 1520M 8192B 0 0 0 0 0 0 0 0 201 62 660 0 > 0 100 > 0 0 0 1520M 8192B 0 0 0 0 0 0 0 0 101 28 404 0 > 0 100 > 0 0 0 1520M 8192B 0 0 0 0 0 0 0 0 97 27 398 0 > 0 100 > 0 0 0 1520M 8192B 0 0 0 0 0 0 0 0 93 28 377 0 > 0 100 > 0 0 0 1520M 8192B 0 0 0 0 0 0 0 0 92 27 373 0 > 0 100 > > > I’d go from a decent amount of free memory to suddenly having none. Vmstat > would stop outputting, console commands would hang, etc. The whole system > would be useless. > > Looking into this, I came across a similar issue; > > https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=199189 > > I started increasing v.v_free_min, and it helped – My crashes went from > being ~every 6 hours to every few days. > > Currently I’m running with vm.v_free_min=1254507 – That’s (1254507 * 4KiB) , > or 4.78GiB of Reserve. The vmstat above is of a machine with that setting > still running to 8B of memory. > > I have two issues here: > > 1) I don’t think I should ever be able to run the system into the ground on > memory. Deny me new memory until the pager can free more. > 2) Setting ‘min’ doesn’t really mean ‘min’ as it can obviously go below that > threshold. > > > I have plenty of local UFS swap (non-ZFS drives) > > Adrian requested that I output a few more diagnostic items, and this is > what I’m running on a console now, in a loop: > > vmstat > netstat -m > vmstat -z > sleep 1 > > The output of four crashes are attached here, as they can be a bit long. Let > me know if that’s not a good way to report them. They will each start > mid-way through a vmstat –z output, as that’s as far back as my terminal > buffer allows. > > > > Now, I have a good idea of the conditions that are causing this: ZFS > Snapshots, run by cron, during times of high ZFS writes. > > The crashes are all nearly on the hour, as that’s when crontab triggers my > python scripts to make new snapshots, and delete old ones. > > My average FreeBSD machine has ~ 30 zfs datasets, with each pool having ~20 > TiB used. These all need to snapshot on the hour. > > By staggering the snapshots by a few minutes, I have been able to reduce > crashing from every other day to perhaps once a week if I’m lucky – But if I > start moving a lot of data around, I can cause daily crashes again. > > It’s looking to be the memory demand of snapshotting lots of ZFS datasets at > the same time while accepting a lot of write traffic. > > Now perhaps the answer is ‘don’t do that’ but I feel that FreeBSD should be > robust enough to handle this. I don’t mind tuning for now to > reduce/eliminate this, but others shouldn’t run into this pain just because > they heavily load their machines – There must be a way of avoiding this > condition. > > Here are the contents of my /boot/loader.conf and sysctl.conf, so show my > minimal tuning to make this problem a little more bearable: > > /boot/loader.conf > vfs.zfs.arc_meta_limit=49656727553 > vfs.zfs.arc_max = 91489280512 > > /etc/sysctl.conf > vm.v_free_min=1254507 > > > Any suggestions/help is appreciated. > > Thank you. > _______________________________________________ freebsd-stable@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscr...@freebsd.org"
