Re: [ovirt-users] oVirt selft-hosted with NFS on top gluster

On Thu, Sep 7, 2017 at 10:30 AM, Yaniv Kaul <ykaul(a)redhat.com&gt; wrote: > > > On Thu, Sep 7, 2017 at 10:06 AM, Yaniv Kaul <ykaul(a)redhat.com&gt; wrote: > >> >> >> On Wed, Sep 6, 2017 at 6:08 PM, Abi Askushi <rightkicktech(a)gmail.com&gt; >> wrote: >> >>> For a first idea I use: >>> >>> dd if=/dev/zero of=testfile bs=1GB count=1 >>> >> >> This is an incorrect way to test performance, for various reasons: >> 1. You are not using oflag=direct , thus not using DirectIO, but using >> cache. >> 2. It's unrealistic - it is very uncommon to write large blocks of zeros >> (sometimes during FS creation or wiping). Certainly not 1GB >> 3. It is a single thread of IO - again, unrealistic for VM's IO. >> >> I forgot to mention that I include oflag=direct in my tests. I agree though that dd is not the correct way to test, hence I mentioned I just use it to get a first feel. More tests are done within the VM benchmarking its disk IO (with tools like IOmeter). I suggest using fio and such. See https://github.com/pcuzner/fio-tools >> for example. >> > Do you have any recommended config file to use for VM workload?

>> >>> >>> When testing on the gluster mount point using above command I hardly >>> get 10MB/s. (On the same time the network traffic hardly reaches 100Mbit). >>> >>> When testing our of the gluster (for example at /root) I get 600 - >>> 700MB/s. >>> >> >> That's very fast - from 4 disks doing RAID5? Impressive (unless you use >> caching!). Are those HDDs or SSDs/NVMe? >> >> > These are SAS disks. But there is also a RAID controller with 1GB cache. >>> When I mount the gluster volume with NFS and test on it I get 90 - 100 >>> MB/s, (almost 10x from gluster results) which is the max I can get >>> considering I have only 1 Gbit network for the storage. >>> >>> Also, when using glusterfs the general VM performance is very poor and >>> disk write benchmarks show that is it at least 4 times slower then when the >>> VM is hosted on the same data store when NFS mounted. >>> >>> I don't know why I hitting such a significant performance penalty, and >>> every possible tweak that I was able to find out there did not make any >>> difference on the performance. >>> >>> The hardware I am using is pretty decent for the purposes intended: >>> 3 nodes, each node having with 32 MB of RAM, 16 physical CPU cores, 2 >>> TB of storage in RAID5 (4 disks), of which 1.5 TB are sliced for the data >>> store of ovirt where VMs are stored. >>> >> > I forgot to ask why are you using RAID 5 with 4 disks and not RAID 10? > Same usable capacity, higher performance, same protection and faster > recovery, I believe. > Correction: there are 5 disks of 600GB each. The main reason going with RAID 5 was the capacity. With RAID 10 I can use only 4 of them and get only 1.1 TB usable, with RAID 5 I get 2.2 TB usable. I agree going with RAID 10 (+ one additional drive to go with 6 drives) would be better but this is what I have now. Y. > > >> You have not mentioned your NIC speeds. Please ensure all work well, >> with 10g. >> Is the network dedicated for Gluster traffic? How are they connected? >> >> > I have mentioned that I have 1 Gbit dedicated for the storage. A different network is used for this and a dedicated 1Gbit switch. The throughput has been confirmed between all nodes with iperf.

I know 10Gbit would be better, but when using native gluster at ovirt the network pipe was hardly reaching 100Mbps thus the bottleneck was gluster and not the network. If I can saturate 1Gbit and I still have performance issues then I may think to go with 10Gbit. With NFS on top gluster I see traffic reaching 800Mbit when testing with dd which is much better.

>>> The gluster configuration is the following: >>> >> >> Which version of Gluster are you using? >> >> > The version is 3.8.12

>>> Volume Name: vms >>> Type: Replicate >>> Volume ID: 4513340d-7919-498b-bfe0-d836b5cea40b >>> Status: Started >>> Snapshot Count: 0 >>> Number of Bricks: 1 x (2 + 1) = 3 >>> Transport-type: tcp >>> Bricks: >>> Brick1: gluster0:/gluster/vms/brick >>> Brick2: gluster1:/gluster/vms/brick >>> Brick3: gluster2:/gluster/vms/brick (arbiter) >>> Options Reconfigured: >>> nfs.export-volumes: on >>> nfs.disable: off >>> performance.readdir-ahead: on >>> transport.address-family: inet >>> performance.quick-read: off >>> performance.read-ahead: off >>> performance.io-cache: off >>> performance.stat-prefetch: on >>> >> >> I think this should be off. >> >> >>> performance.low-prio-threads: 32 >>> network.remote-dio: off >>> >> >> I think this should be enabled. >> >> >>> cluster.eager-lock: off >>> cluster.quorum-type: auto >>> cluster.server-quorum-type: server >>> cluster.data-self-heal-algorithm: full >>> cluster.locking-scheme: granular >>> cluster.shd-max-threads: 8 >>> cluster.shd-wait-qlength: 10000 >>> features.shard: on >>> user.cifs: off >>> storage.owner-uid: 36 >>> storage.owner-gid: 36 >>> network.ping-timeout: 30 >>> performance.strict-o-direct: on >>> cluster.granular-entry-heal: enable >>> features.shard-block-size: 64MB >>> >> >> I'm not sure if this should not be 512MB. I don't remember the last >> resolution on this. >> Y. >> >> >>> performance.client-io-threads: on >>> client.event-threads: 4 >>> server.event-threads: 4 >>> performance.write-behind-window-size: 4MB >>> performance.cache-size: 1GB >>> >>> I have been playing with all above with very little difference on performance I was getting. In case I can provide any other details let me know. >>> >> >> What is your tuned profile? >> >> > the tuned profile is virtual-host At the moment I already switched to gluster based NFS but I have a similar >>> setup with 2 nodes where the data store is mounted through gluster (and >>> again relatively good hardware) where I might check any tweaks or >>> improvements on this setup. >>> >>> Thanx >>> >>> >>> On Wed, Sep 6, 2017 at 5:32 PM, Yaniv Kaul <ykaul(a)redhat.com&gt; wrote: >>> >>>> >>>> >>>> On Wed, Sep 6, 2017 at 3:32 PM, Abi Askushi <rightkicktech(a)gmail.com&gt; >>>> wrote: >>>> >>>>> Hi All, >>>>> >>>>> I've playing with ovirt self hosted engine setup and I even use it to >>>>> production for several VM. The setup I have is 3 server with gluster >>>>> storage in replica 2+1 (1 arbiter). >>>>> The data storage domain where VMs are stored is mounted with gluster >>>>> through ovirt. The performance I get for the VMs is very low and I was >>>>> thinking to switch and mount the same storage through NFS instead of >>>>> glusterfs. >>>>> >>>> >>>> I don't see how it'll improve performance. >>>> I suggest you share the gluster configuration (as well as the storage >>>> HW) so we can understand why the performance is low. >>>> Y. >>>> >>>> >>>>> >>>>> The only think I am hesitant is how can I ensure high availability of >>>>> the storage when I loose one server? I was thinking to have at /etc/hosts >>>>> sth like below: >>>>> >>>>> 10.100.100.1 nfsmount >>>>> 10.100.100.2 nfsmount >>>>> 10.100.100.3 nfsmount >>>>> >>>>> then use nfsmount as the server name when adding this domain through >>>>> ovirt GUI. >>>>> Are there any other more elegant solutions? What do you do for such >>>>> cases? >>>>> Note: gluster has the back-vol-file option which provides a lean way >>>>> to have redundancy on the mount point and I am using this when mounting >>>>> with glusterfs. >>>>> >>>>> Thanx >>>>> >>>>> _______________________________________________ >>>>> Users mailing list >>>>> Users(a)ovirt.org >>>>> http://lists.ovirt.org/mailman/listinfo/users >>>>> >>>>> >>>> >>> >> >