[lustre-discuss] how to optimize write performances

Riccardo Veraldi riccardo.veraldi at cnaf.infn.it
Thu Sep 30 09:09:53 PDT 2021


Hello,

I wanted to ask some hint on how I may increase single process 
sequential write performance on Lustre.

I am using Lustre 2.12.7 on RHEL 7.9

I have a number of OSSes with SAS SSDs in raidz. 3 OST per oss and each 
OST is made by 8 SSD in raidz.

On a local test with multiple writes I can write and read from the zpool 
at 7GB/s per OSS.

With Lustre/ZFS backend I can reach peak writes of 5.5GB/s per OSS which 
is ok.

This anyway happens only with several multiple writes at once on the 
filesystem.

A single write cannot perform more than 800MB-1GB/s

Changing the underlying hardware and moving to MVMe slightly improve 
single write performance but just slightly.

What is preventing a single write pattern to perform better ? They are 
XTC files.

Each single SSD has a 500MB/s write capability by factory specs. So 
seems like that with a single write it is not possible to take advantage 
of the

zpool parallelism. I tried also striping but that does not really help much.

Any hint is really appreciated.

Best

Riccardo





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