XFS discards more data than it writes
Jun He <[email protected]>
| Newsgroups | gmane.comp.file-systems.xfs.general |
|---|---|
| Message-ID | <[email protected]> |
Hi all, I find that, with '-o discard', XFS sometimes discards more data than it writes. This may slow down XFS more on slow-discard SSDs. Also, could problematic discard implementation lead to data loss? Setup to reproduce: - Linux 4.5.4 - Workload: LevelDB $ mkfs.xfs -K -f -s size=4096 -b size=4096 /dev/sdc1 $ mount -o discard /dev/sdc1 /mnt/fsonloop $ leveldb/db_bench --benchmarks=overwrite --num=3000000 --db=/mnt/fsonloop/leveldb_data0 --threads=1 --use_existing_db=0 I found that XFS discarded ~2.4GB while only wrote ~1.4GB, by blktrace. (This is not due to the mkfs discarding the whole disk.) Some visual https://github.com/junhe/xfs-bug-report/blob/master/xfs-double-discard.png Some spaces are discarded twice in this case. Is it a bug? Thanks, Jun _______________________________________________ xfs mailing list [email protected] http://oss.sgi.com/mailman/listinfo/xfs