On Wed, 31 Dec 2008, Ricky Zhou wrote: > On 2008-12-31 10:49:56 PM, Xavier Lamien wrote: > > Could you perform an hdparm -tT on that disk ? > /dev/sde: > Timing cached reads: 2668 MB in 2.00 seconds = 1336.06 MB/sec > Timing buffered disk reads: 1024 MB in 3.01 seconds = 340.69 MB/sec > > > Also, output an strace against your cat & dd commands. > > > > if my memory is good enough, cat use mmap() which is faster than > > read() (which is used by dd) > I just straced dd and cat, and it looks like cat is using a block size > of 4096 bytes while dd is using 512 bytes. I *think* they were both > just using read(). Perhaps dd if=/dev/sde of=/dev/null bs=4096 would be > a better command to compare against. > Ok, that explains the difference between dd and cat. Now why is the rest of it so bad. -Mike _______________________________________________ Fedora-infrastructure-list mailing list Fedora-infrastructure-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/fedora-infrastructure-list
