[Gluster-users] Expected performance for WORM scenario

Nithya Balachandran nbalacha at redhat.com
Mon Mar 12 14:30:48 UTC 2018


Can you send us the following details:
1. gluster volume info
2. What client you are using to run this?


On 12 March 2018 at 18:16, Andreas Ericsson <andreas.ericsson at findity.com>

> Heya fellas.
> I've been struggling quite a lot to get glusterfs to perform even
> halfdecently with a write-intensive workload. Testnumbers are from gluster
> 3.10.7.
> We store a bunch of small files in a doubly-tiered sha1 hash fanout
> directory structure. The directories themselves aren't overly full. Most of
> the data we write to gluster is "write once, read probably never", so 99%
> of all operations are of the write variety.
> The network between servers is sound. 10gb network cards run over a 10gb
> (doh) switch. iperf reports 9.86Gbit/sec. ping reports a latency of 0.1 -
> 0.2 ms. There is no firewall, no packet inspection and no nothing between
> the servers, and the 10gb switch is the only path between the two machines,
> so traffic isn't going over some 2mbit wifi by accident.
> Our main storage has always been really slow (write speed of roughly
> 1.5MiB/s), but I had long attributed that to the extremely slow disks we
> use to back it, so now that we're expanding I set up a new gluster cluster
> with state of the art NVMe SSD drives to boost performance. However,
> performance only hopped up to around 2.1MiB/s. Perplexed, I tried it first
> with a 3-node cluster using 2GB ramdrives, which got me up to 2.4MiB/s. My
> last resort was to use a single node running on ramdisk, just to 100%
> exclude any network shenanigans, but the write performance stayed at an
> absolutely abysmal 3MiB/s.
> Writing straight to (the same) ramdisk gives me "normal" ramdisk speed (I
> don't actually remember the numbers, but my test that took 2 minutes with
> gluster completed before I had time to blink). Writing straight to the
> backing SSD drives gives me a throughput of 96MiB/sec.
> The test itself writes 8494 files that I simply took randomly from our
> production environment, comprising a total of 63.4MiB (so average file size
> is just under 8k. Most are actually close to 4k though, with the occasional
> 2-or-so MB file in there.
> I have googled and read a *lot* of performance-tuning guides, but the
> 3MiB/sec on single-node ramdisk seems to be far beyond the crippling one
> can cause by misconfiguration of a single system.
> With this in mind; What sort of write performance can one reasonably hope
> to get with gluster? Assume a 3-node cluster running on top of (small)
> ramdisks on a fast and stable network. Is it just a bad fit for our
> workload?
> /Andreas
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