I'm using Ubuntu 12.04 with 2 x 2TB SATA3 harddisks in software RAID1. The filesystem is ext4 with data=writeback
.
When using find . -maxdepth 1 -name '*' -delete
to delete a large number of files in a directory, doing df
at intervals show that:
Initially a large number of files get deleted, and iotop
shows the find
operation taking most of the IO.
Later df
shows that the number of files remain constant, and iotop
shows that IO usage is now dominated by jbd2
and md4_raid1
.
Few minutes later, df
shows the number of files dropping once more.
Can anyone explain this behavior? Is this normal or is there something wrong with my server? Also, how can 3 processes all have 99.99% IO usage at the same time?