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 <[email protected]> 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
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