eio_cli delete - why are you so slow?

[HJarausch]

Given, the underlying hard disk is not that fast.
fio reports about 36 Mb/sec in sequential write.

But "eio_cli delete" writes only 8 Mb/sec.
I've done a fio test with 10G on the cached FS which was showed about 225 Mb/sec.
Then I tried to delete the cache.
It wrote only 1024 blocks (a 8K) per second.

[rezass]

Can you run iostat -Ntx -y -d 5 when cache is flushing and see the main disk utilization?
Flushing cache will not necessarily send sequential requests to the disk.