Re: File system performance, hardware performance, ext3, 3ware RAID1, etc.

[Eric D. Mudama]

On Fri, Feb 13 at  6:53, Willy Tarreau wrote:
> It depends on the disk too. Lots of disks (specially IDE) are far slower
> on writes than they are on reads.

This may be a function of the operating system or the filesystem, but
it isn't necessarilly an artifact of the drives themselves.  With both
read and write caching enabled, random writes will always be faster
than random reads from the drive perspective.

Even with queueing enabled (legacy TCQ or Native-SATA "NCQ"), your
ability to reorder reads is limited in ATA to 32 tags, while the
ability to reorder cached writes is limited only by buffer size and
cache granularity...  the absolute worst-case write performance should
be the same as read performance.

--eric


--
Eric D. Mudama
edmudama@xxxxxxxxxxxxxxxxxxxxx

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/