[gpfsug-discuss] sequential I/O write - performance tuning

[Aaron Knister]

What does iostat output look like when you’re running the tests on GPFS? It would be good to confirm that GPFS is successfully submitting 2MB I/o requests. 

Sent from my iPhone

> On Feb 7, 2024, at 08:08, Michal Hruška <Michal.Hruska at mcomputers.cz> wrote:
> 
> 
> Dear gpfsUserGroup,
>  
> we are dealing with new gpfs cluster (Storage Scale 5.1.9 – RHEL 9.3) [3 FE servers and one storage system] and some performance issues.
> We were able to tune underlying storage system to get to performance ~4500 MiB/s from 8 RAID groups using XFS (one XFS per one RAID group) and parallel fio test.
> Once we installed the gpfs – one FS accross all 8 RAID groups and we observed performance drop down to ~3300 MiB/s using the same fio test.
> All tests were performed from one front-end node connected directly to the storage system via FibreChannel (4 paths each path is 32GFC).
>  
> Storage systems RAID groups are sized to fit 2MB data blocks to utilize full-stripe writes as the RAID geometry is 8+2 using 256KB block size -> 8*256KB = 2MB.
> I/O pattern on FC is optimized too.
> GPFS metadata were moved to NVMe SSDs on different storage system.
> We already tried some obvious troubleshooting on gpfs side like: maxMBpS, scatter/cluster, different block sizes and some other parameters but there is no performance gain.
>  
> We were advised that gpfs might not perform pure sequential writes towards the storage system and therefore the storage system is performing more random I/O than sequential.
>  
> Could you please share with us some thougths about how to make gpfs as much sequential as possible? The goal is to reach at least 4000 MiB/s for sequential writes/reads.
>  
> best regards,
> Michal Hruška
> 
> 
>  
> _______________________________________________
> gpfsug-discuss mailing list
> gpfsug-discuss at gpfsug.org
> http://gpfsug.org/mailman/listinfo/gpfsug-discuss_gpfsug.org
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://gpfsug.org/pipermail/gpfsug-discuss_gpfsug.org/attachments/20240207/2d9bec90/attachment.htm>