It could be Multi-Mount Protection (MMP)? Cheers, Andreas
> On Oct 7, 2025, at 08:52, Alex Vodeyko via lustre-discuss > <[email protected]> wrote: > > Hi, > > I'm in the process of testing lustre-2.15.7_next on rocky-9.6, kernel > 5.14.0-570.17.1.el9_6.x86_64, zfs-2.3.4. > 84 disk shelf, multipath. > 2x OSTs per OSS > OST is on the zpool with 4x(8+2)raidz2=40 hdds configuration (btw - > also tested on draid - the same problem). > atime=off (also tested with relatime=on) > recordsize=1M, compression=off > > During benchmarks I've found that even on the completely idle system, > zpool-iostat shows 40-160 4k (ashift=12) writes (1-4 per hdd) every > second. > # zpool iostat 1 > capacity operations bandwidth > pool alloc free read write read write > ---------- ----- ----- ----- ----- ----- ----- > .. > ost00 482G 145T 0 158 0 634K > ost01 401G 145T 0 40 0 161K > ---------- ----- ----- ----- ----- ----- ----- > ost00 482G 145T 0 40 0 161K > ost01 401G 145T 0 157 0 629K > ---------- ----- ----- ----- ----- ----- ----- > ost00 482G 145T 0 40 0 161K > ost01 401G 145T 0 40 0 161K > ---------- ----- ----- ----- ----- ----- ----- > ost00 482G 145T 0 38 0 153K > ost01 401G 145T 0 39 0 157K > > Could you please advise if I can turn off something (probably in > lustre, because local zfs does not show this behaviour) to avoid these > writes because they affect read performance (and cause huge cpu load > average and iowait numbers especially during multiple concurrent reads > from the single OST). > > Many thanks, > Alex > _______________________________________________ > lustre-discuss mailing list > [email protected] > http://lists.lustre.org/listinfo.cgi/lustre-discuss-lustre.org _______________________________________________ lustre-discuss mailing list [email protected] http://lists.lustre.org/listinfo.cgi/lustre-discuss-lustre.org
