[Gluster-users] performance - what can I expect

[Pascal Suter]

i continued my testing with 5 clients, all attached over 100Gbit/s 
omni-path via IP over IB. when i run the same iozone benchmark across 
all 5 clients where gluster is mounted using the glusterfs client, i get 
an aggretated write throughput of only about 400GB/s and an aggregated 
read throughput of 1.5GB/s. Each node was writing a single 200Gb file in 
16MB chunks and the files where distributed across all three bricks on 
the server.

the connection was established over Omnipath for sure, as there is no 
other link between the nodes and server.

i have no clue what i'm doing wrong here. i can't believe that this is a 
normal performance people would expect to see from gluster. i guess 
nobody would be using it if it was this slow.

again, when written dreictly to the xfs filesystem on the bricks, i get 
over 6GB/s read and write throughput using the same benchmark.

any advise is appreciated

cheers

Pascal

On 04.04.19 12:03, Pascal Suter wrote:
> I just noticed i left the most important parameters out :)
>
> here's the write command with filesize and recordsize in it as well :)
>
> ./iozone -i 0 -t 1 -F /mnt/gluster/storage/thread1 -+n -c -C -e -I -w 
> -+S 0 -s 200G -r 16384k
>
> also i ran the benchmark without direct_io which resulted in an even 
> worse performance.
>
> i also tried to mount the gluster volume via nfs-ganesha which further 
> reduced throughput down to about 450MB/s
>
> if i run the iozone benchmark with 3 threads writing to all three 
> bricks directly (from the xfs filesystem) i get throughputs of around 
> 6GB/s .. if I run the same benchmark through gluster mounted locally 
> using the fuse client and with enough threads so that each brick gets 
> at least one file written to it, i end up seing throughputs around 
> 1.5GB/s .. that's a 4x decrease in performance. at it actually is the 
> same if i run the benchmark with less threads and files only get 
> written to two out of three bricks.
>
> cpu load on the server is around 25% by the way, nicely distributed 
> across all available cores.
>
> i can't believe that gluster should really be so slow and everybody is 
> just happily using it. any hints on what i'm doing wrong are very 
> welcome.
>
> i'm using gluster 6.0 by the way.
>
> regards
>
> Pascal
>
> On 03.04.19 12:28, Pascal Suter wrote:
>> Hi all
>>
>> I am currently testing gluster on a single server. I have three 
>> bricks, each a hardware RAID6 volume with thin provisioned LVM that 
>> was aligned to the RAID and then formatted with xfs.
>>
>> i've created a distributed volume so that entire files get 
>> distributed across my three bricks.
>>
>> first I ran a iozone benchmark across each brick testing the read and 
>> write perofrmance of a single large file per brick
>>
>> i then mounted my gluster volume locally and ran another iozone run 
>> with the same parameters writing a single file. the file went to 
>> brick 1 which, when used driectly, would write with 2.3GB/s and read 
>> with 1.5GB/s. however, through gluster i got only 800MB/s read and 
>> 750MB/s write throughput
>>
>> another run with two processes each writing a file, where one file 
>> went to the first brick and the other file to the second brick (which 
>> by itself when directly accessed wrote at 2.8GB/s and read at 
>> 2.7GB/s) resulted in 1.2GB/s of aggregated write and also aggregated 
>> read throughput.
>>
>> Is this a normal performance i can expect out of a glusterfs or is it 
>> worth tuning in order to really get closer to the actual brick 
>> filesystem performance?
>>
>> here are the iozone commands i use for writing and reading.. note 
>> that i am using directIO in order to make sure i don't get fooled by 
>> cache :)
>>
>> ./iozone -i 0 -t 1 -F /mnt/brick${b}/thread1 -+n -c -C -e -I -w -+S 0 
>> -s $filesize -r $recordsize > iozone-brick${b}-write.txt
>>
>> ./iozone -i 1 -t 1 -F /mnt/brick${b}/thread1 -+n -c -C -e -I -w -+S 0 
>> -s $filesize -r $recordsize > iozone-brick${b}-read.txt
>>
>> cheers
>>
>> Pascal
>>
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