From: Sahina Bose <sabose@redhat.com>
Subject: [ovirt-users] Re: Ovirt cluster unstable; gluster to blame (again)
Date: July 9, 2018 at 10:42:15 AM CDT
To: Edward Clay; Jim Kusznir
Cc: users
_______________________________________________see response about bug at https://lists.ovirt.org/archives/list/users@ovirt.org/thread/WRYEBOLNHJZGKKJUNF77TJ7WMBS66ZYK/ which seems to indicate the referenced bug is fixed at 3.12.2 and higher.Could you attach the statedump of the process to the bug https://bugzilla.redhat.com/show_bug.cgi?id=1593826 as requested?On Mon, Jul 9, 2018 at 8:38 PM, Edward Clay <edward.clay@uk2group.com> wrote:Just to add my .02 here. I've opened a bug on this issue where HV/host connected to clusterfs volumes are running out of ram. This seemed to be a bug fixed in gluster 3.13 but that patch doesn't seem to be avaiable any longer and 3.12 is what ovirt is using. For example I have a host that was showing 72% of memory consumption with 3 VMs running on it. If I migrate those VMs to another Host memory consumption drops to 52%. If i put this host into maintenance and then activate it it drops down to 2% or so. Since I ran into this issue I've been manually watching memory consumption on each host and migrating VMs from it to others to keep things from dying. I'm hoping with the announcement of gluster 3.12 end of life and the move to gluster 4.1 that this will get fixed or that the patch from 3.13 can get backported so this problem will go away.
https://bugzilla.redhat.com/
show_bug.cgi?id=1593826
On 07/07/2018 11:49 AM, Jim Kusznir wrote:
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This host has NO VMs running on it, only 3 running cluster-wide (including the engine, which is on its own storage):
top - 10:44:41 up 1 day, 17:10, 1 user, load average: 15.86, 14.33, 13.39Tasks: 381 total, 1 running, 379 sleeping, 1 stopped, 0 zombie%Cpu(s): 2.7 us, 2.1 sy, 0.0 ni, 89.0 id, 6.1 wa, 0.0 hi, 0.2 si, 0.0 stKiB Mem : 32764284 total, 338232 free, 842324 used, 31583728 buff/cacheKiB Swap: 12582908 total, 12258660 free, 324248 used. 31076748 avail Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND13279 root 20 0 2380708 37628 4396 S 51.7 0.1 3768:03 glusterfsd13273 root 20 0 2233212 20460 4380 S 17.2 0.1 105:50.44 glusterfsd13287 root 20 0 2233212 20608 4340 S 4.3 0.1 34:27.20 glusterfsd16205 vdsm 0 -20 5048672 88940 13364 S 1.3 0.3 0:32.69 vdsmd16300 vdsm 20 0 608488 25096 5404 S 1.3 0.1 0:05.78 python1109 vdsm 20 0 3127696 44228 8552 S 0.7 0.1 18:49.76 ovirt-ha-broker25555 root 20 0 0 0 0 S 0.7 0.0 0:00.13 kworker/u64:310 root 20 0 0 0 0 S 0.3 0.0 4:22.36 rcu_sched572 root 0 -20 0 0 0 S 0.3 0.0 0:12.02 kworker/1:1H797 root 20 0 0 0 0 S 0.3 0.0 1:59.59 kdmwork-253:2877 root 0 -20 0 0 0 S 0.3 0.0 0:11.34 kworker/3:1H1028 root 20 0 0 0 0 S 0.3 0.0 0:35.35 xfsaild/dm-101869 root 20 0 1496472 10540 6564 S 0.3 0.0 2:15.46 python3747 root 20 0 0 0 0 D 0.3 0.0 0:01.21 kworker/u64:110979 root 15 -5 723504 15644 3920 S 0.3 0.0 22:46.27 glusterfs15085 root 20 0 680884 10792 4328 S 0.3 0.0 0:01.13 glusterd16102 root 15 -5 1204216 44948 11160 S 0.3 0.1 0:18.61 supervdsmd
At the moment, the engine is barely usable, my other VMs appear to be unresponsive. Two on one host, one on another, and none on the third.
On Sat, Jul 7, 2018 at 10:38 AM, Jim Kusznir <jim@palousetech.com> wrote:
I run 4-7 VMs, and most of them are 2GB ram. I have 2 VMs with 4GB.
Ram hasn't been an issue until recent ovirt/gluster upgrades. Storage has always been slow, especially with these drives. However, even watching network utilization on my switch, the gig-e links never max out.
The loadavg issues and unresponsive behavior started with yesterday's ovirt updates. I now have one VM with low I/O that lives on a separate storage volume (data, fully SSD backed instead of data-hdd, which was having the issues). I moved it to a ovirt host with no other VMs on it, and that had reshly been rebooted. Before it had this one VM on it, loadavg was >0.5. Now its up in the 20's, with only one low Disk I/O, 4GB ram VM on the host.
This to me says there's now a new problem separate from Gluster. I don't have any non-gluster storage available to test with. I did notice that the last update included a new kernel, and it appears its the qemu-kvm processes that are consuming way more CPU than they used to now.
Are there any known issues? I'm going to reboot into my previous kernel to see if its kernel-caused.
--Jim
On Fri, Jul 6, 2018 at 11:07 PM, Johan Bernhardsson <johan@kafit.se> wrote:
That is a single sata drive that is slow on random I/O and that has to be synced with 2 other servers. Gluster works syncronous so one write has to be written and acknowledged on all the three nodes.
So you have a bottle neck in io on drives and one on network and depending on how many virtual servers you have and how much ram they take you might have memory.
Load spikes when you have a wait somewhere and are overusing capacity. But it's now only CPU that load is counted on. It is waiting for resources so it can be memory or Network or drives.
How many virtual server do you run and how much ram do they consume?
On July 7, 2018 09:51:42 Jim Kusznir <jim@palousetech.com> wrote:
In case it matters, the data-hdd gluster volume uses these hard drives:
This is in a Dell R610 with PERC6/i (one drive per server, configured as a single drive volume to pass it through as its own /dev/sd* device). Inside the OS, its partitioned with lvm_thin, then an lvm volume formatted with XFS and mounted as /gluster/brick3, with the data-hdd volume created inside that.
--Jim
On Fri, Jul 6, 2018 at 10:45 PM, Jim Kusznir <jim@palousetech.com> wrote:
So, I'm still at a loss...It sounds like its either insufficient ram/swap, or insufficient network. It seems to be neither now. At this point, it appears that gluster is just "broke" and killing my systems for no descernable reason. Here's detals, all from the same system (currently running 3 VMs):
[root@ovirt3 ~]# w22:26:53 up 36 days, 4:34, 1 user, load average: 42.78, 55.98, 53.31USER TTY FROM LOGIN@ IDLE JCPU PCPU WHATroot pts/0 192.168.8.90 22:26 2.00s 0.12s 0.11s w
bwm-ng reports the highest data usage was about 6MB/s during this test (and that was combined; I have two different gig networks. One gluster network (primary VM storage) runs on one, the other network handles everything else).
[root@ovirt3 ~]# free -mtotal used free shared buff/cache availableMem: 31996 13236 232 18 18526 18195Swap: 16383 1475 14908
top - 22:32:56 up 36 days, 4:41, 1 user, load average: 17.99, 39.69, 47.66Tasks: 407 total, 1 running, 405 sleeping, 1 stopped, 0 zombie%Cpu(s): 8.6 us, 2.1 sy, 0.0 ni, 87.6 id, 1.6 wa, 0.0 hi, 0.1 si, 0.0 stKiB Mem : 32764284 total, 228296 free, 13541952 used, 18994036 buff/cacheKiB Swap: 16777212 total, 15246200 free, 1531012 used. 18643960 avail Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND30036 qemu 20 0 6872324 5.2g 13532 S 144.6 16.5 216:14.55 /usr/libexec/qemu-kvm -name guest=BillingWin,debug-threads=on -S -object secret,id=masterKey0,format=ra w,file=/v+ 28501 qemu 20 0 5034968 3.6g 12880 S 16.2 11.7 73:44.99 /usr/libexec/qemu-kvm -name guest=FusionPBX,debug-threads=on -S -object secret,id=masterKey0,format=ra w,file=/va+ 2694 root 20 0 2169224 12164 3108 S 5.0 0.0 3290:42 /usr/sbin/glusterfsd -s ovirt3.nwfiber.com --volfile-id data.ovirt3.nwfiber.com.gluster-brick2-data -p /var/run/+ 14293 root 15 -5 944700 13356 4436 S 4.0 0.0 16:32.15 /usr/sbin/glusterfs --volfile-server=192.168.8.11 --volfile-server=192.168.8.12 --volfile-server=192.168.8.13 --+25100 vdsm 0 -20 6747440 107868 12836 S 2.3 0.3 21:35.20 /usr/bin/python2 /usr/share/vdsm/vdsmd28971 qemu 20 0 2842592 1.5g 13548 S 1.7 4.7 241:46.49 /usr/libexec/qemu-kvm -name guest=unifi.palousetech.com,debug-threads=on -S -object secret,id=masterKey0,format=+ 12095 root 20 0 162276 2836 1868 R 1.3 0.0 0:00.25 top2708 root 20 0 1906040 12404 3080 S 1.0 0.0 1083:33 /usr/sbin/glusterfsd -s ovirt3.nwfiber.com --volfile-id engine.ovirt3.nwfiber.com.gluster-brick1-engine -p /var/+ 28623 qemu 20 0 4749536 1.7g 12896 S 0.7 5.5 4:30.64 /usr/libexec/qemu-kvm -name guest=billing.nwfiber.com,debug-threads=on -S -object secret,id=masterKey0,format=ra + 10 root 20 0 0 0 0 S 0.3 0.0 215:54.72 [rcu_sched]1030 sanlock rt 0 773804 27908 2744 S 0.3 0.1 35:55.61 /usr/sbin/sanlock daemon1890 zabbix 20 0 83904 1696 1612 S 0.3 0.0 24:30.63 /usr/sbin/zabbix_agentd: collector [idle 1 sec]2722 root 20 0 1298004 6148 2580 S 0.3 0.0 38:10.82 /usr/sbin/glusterfsd -s ovirt3.nwfiber.com --volfile-id iso.ovirt3.nwfiber.com.gluster-brick4-iso -p /var/run/gl+ 6340 root 20 0 0 0 0 S 0.3 0.0 0:04.30 [kworker/7:0]10652 root 20 0 0 0 0 S 0.3 0.0 0:00.23 [kworker/u64:2]14724 root 20 0 1076344 17400 3200 S 0.3 0.1 10:04.13 /usr/sbin/glusterfs -s localhost --volfile-id gluster/glustershd -p /var/run/gluster/glustershd/glustershd.pid -+22011 root 20 0 0 0 0 S 0.3 0.0 0:05.04 [kworker/10:1]
Not sure why the system load dropped other than I was trying to take a picture of it :)
In any case, it appears that at this time, I have plenty of swap, ram, and network capacity, and yet things are still running very sluggish; I'm still getting e-mails from servers complaining about loss of communication with something or another; I still get e-mails from the engine about bad engine status, then recovery, etc.
I've shut down 2/3 of my VMs, too....just trying to keep the critical ones operating.
At this point, I don't believe the problem is the memory leak, but it seems to be triggered by the memory leak, as in all my problems started when I got low ram warnings from one of my 3 nodes and began recovery efforts from that.
I do really like the idea / concept behind glusterfs, but I really have to figure out why its been so poor performing from day one, and its caused 95% of my outages (including several large ones lately). If I can get it stable, reliable, and well performing, then I'd love to keep it. If I can't, then perhaps NFS is the way to go? I don't like the single point of failure aspect of it, but my other NAS boxes I run for clients (central storage for windows boxes) have been very solid; If I could get that kind of reliability for my ovirt stack, it would be a substantial improvement. Currently, it seems about every other month I have a gluster-induced outage.
Sometimes I wonder if its just hyperconverged is the issue, but my infrastructure doesn't justify three servers at the same location...I might be able to do two, but even that seems like its pushing it.
Looks like I can upgrade to 10G for about $900. I can order a dual-Xeon supermicro 12-disk server, loaded with 2TB WD Enterprise disks and a pair of SSDs for the os, 32GB ram, 2.67Ghz CPUs for about $720 delivered. I've got to do something to improve my reliability; I can't keep going the way I have been....
--Jim
On Fri, Jul 6, 2018 at 9:13 PM, Johan Bernhardsson <johan@kafit.se> wrote:
Load like that is mostly io based either the machine is swapping or network is to slow. Check I/o wait in top.
And the problem where you get oom killer to kill off gluster. That means that you don't monitor ram usage on the servers? Either it's eating all your ram and swap gets really io intensive and then is killed off. Or you have the wrong swap settings in sysctl.conf (there are tons of broken guides that recommends swappines to 0 but that disables swap on newer kernels. The proper swappines for only swapping when nesseary is 1 or a sufficiently low number like 10 default is 60)
Moving to nfs will not improve things. You will get more memory since gluster isn't running and that is good. But you will have a single node that can fail with all your storage and it would still be on 1 gigabit only and your three node cluster would easily saturate that link.
On July 7, 2018 04:13:13 Jim Kusznir <jim@palousetech.com> wrote:
So far it does not appear to be helping much. I'm still getting VM's locking up and all kinds of notices from overt engine about non-responsive hosts. I'm still seeing load averages in the 20-30 range.
Jim
On Fri, Jul 6, 2018, 3:13 PM Jim Kusznir <jim@palousetech.com> wrote:
Thank you for the advice and help
I do plan on going 10Gbps networking; haven't quite jumped off that cliff yet, though.
I did put my data-hdd (main VM storage volume) onto a dedicated 1Gbps network, and I've watched throughput on that and never seen more than 60GB/s achieved (as reported by bwm-ng). I have a separate 1Gbps network for communication and ovirt migration, but I wanted to break that up further (separate out VM traffice from migration/mgmt traffic). My three SSD-backed gluster volumes run the main network too, as I haven't been able to get them to move to the new network (which I was trying to use as all gluster). I tried bonding, but that seamed to reduce performance rather than improve it.
--Jim
On Fri, Jul 6, 2018 at 2:52 PM, Jamie Lawrence <jlawrence@squaretrade.com> wrote:
Hi Jim,
I don't have any targeted suggestions, because there isn't much to latch on to. I can say Gluster replica three (no arbiters) on dedicated servers serving a couple Ovirt VM clusters here have not had these sorts of issues.
I suspect your long heal times (and the resultant long periods of high load) are at least partly related to 1G networking. That is just a matter of IO - heals of VMs involve moving a lot of bits. My cluster uses 10G bonded NICs on the gluster and ovirt boxes for storage traffic and separate bonded 1G for ovirtmgmt and communication with other machines/people, and we're occasionally hitting the bandwidth ceiling on the storage network. I'm starting to think about 40/100G, different ways of splitting up intensive systems, and considering iSCSI for specific volumes, although I really don't want to go there.
I don't run FreeNAS[1], but I do run FreeBSD as storage servers for their excellent ZFS implementation, mostly for backups. ZFS will make your `heal` problem go away, but not your bandwidth problems, which become worse (because of fewer NICS pushing traffic). 10G hardware is not exactly in the impulse-buy territory, but if you can, I'd recommend doing some testing using it. I think at least some of your problems are related.
If that's not possible, my next stops would be optimizing everything I could about sharding, healing and optimizing for serving the shard size to squeeze as much performance out of 1G as I could, but that will only go so far.
-j
[1] FreeNAS is just a storage-tuned FreeBSD with a GUI.
> On Jul 6, 2018, at 1:19 PM, Jim Kusznir <jim@palousetech.com> wrote:
>
> hi all:
>
> Once again my production ovirt cluster is collapsing in on itself. My servers are intermittently unavailable or degrading, customers are noticing and calling in. This seems to be yet another gluster failure that I haven't been able to pin down.
>
> I posted about this a while ago, but didn't get anywhere (no replies that I found). The problem started out as a glusterfsd process consuming large amounts of ram (up to the point where ram and swap were exhausted and the kernel OOM killer killed off the glusterfsd process). For reasons not clear to me at this time, that resulted in any VMs running on that host and that gluster volume to be paused with I/O error (the glusterfs process is usually unharmed; why it didn't continue I/O with other servers is confusing to me).
>
> I have 3 servers and a total of 4 gluster volumes (engine, iso, data, and data-hdd). The first 3 are replica 2+arb; the 4th (data-hdd) is replica 3. The first 3 are backed by an LVM partition (some thin provisioned) on an SSD; the 4th is on a seagate hybrid disk (hdd + some internal flash for acceleration). data-hdd is the only thing on the disk. Servers are Dell R610 with the PERC/6i raid card, with the disks individually passed through to the OS (no raid enabled).
>
> The above RAM usage issue came from the data-hdd volume. Yesterday, I cought one of the glusterfsd high ram usage before the OOM-Killer had to run. I was able to migrate the VMs off the machine and for good measure, reboot the entire machine (after taking this opportunity to run the software updates that ovirt said were pending). Upon booting back up, the necessary volume healing began. However, this time, the healing caused all three servers to go to very, very high load averages (I saw just under 200 on one server; typically they've been 40-70) with top reporting IO Wait at 7-20%. Network for this volume is a dedicated gig network. According to bwm-ng, initially the network bandwidth would hit 50MB/s (yes, bytes), but tailed off to mostly in the kB/s for a while. All machines' load averages were still 40+ and gluster volume heal data-hdd info reported 5 items needing healing. Server's were intermittently experiencing IO issues, even on the 3 gluster volumes that appeared largely unaffected. Even the OS activities on the hosts itself (logging in, running commands) would often be very delayed. The ovirt engine was seemingly randomly throwing engine down / engine up / engine failed notifications. Responsiveness on ANY VM was horrific most of the time, with random VMs being inaccessible.
>
> I let the gluster heal run overnight. By morning, there were still 5 items needing healing, all three servers were still experiencing high load, and servers were still largely unstable.
>
> I've noticed that all of my ovirt outages (and I've had a lot, way more than is acceptable for a production cluster) have come from gluster. I still have 3 VMs who's hard disk images have become corrupted by my last gluster crash that I haven't had time to repair / rebuild yet (I believe this crash was caused by the OOM issue previously mentioned, but I didn't know it at the time).
>
> Is gluster really ready for production yet? It seems so unstable to me.... I'm looking at replacing gluster with a dedicated NFS server likely FreeNAS. Any suggestions? What is the "right" way to do production storage on this (3 node cluster)? Can I get this gluster volume stable enough to get my VMs to run reliably again until I can deploy another storage solution?
>
> --Jim
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