IDE drive reads slower with write cache disabled
 

Hi,

I saw a strange thing I can't explain:
I have an IDE disk, FUJITSU MHV2080AS with a PCI controller:

under kernel 2.6.5.

The problem is:
If the disk write cache is enabled,
hdparm -t /dev/hc
measures a read speed of cca. 30 MB/s.

If I disable the disk write cache with
hdparm -W 0 /dev/hdc

then the transfer speed measured drops back to cca. 26 MB/s.
This is reproducible.

This is strange as hdparm -t should perform read tests only, right ?