In-Reply-To: <[email protected]>
On Sat, 15 Jul 2006 17:04:57 -0700, Jonathan Baccash wrote:
> As expected, the multi-threaded reads are 2x as fast as single-threaded
> reads. But I would have expected (assuming the write to both disks can
> occur in parallel) that the random writes are about the same speed (10
> seconds) as the single-threaded random reads, for both the
> single-threaded and multi-threaded write cases. The fact that the
> multi-threaded reads were
> twice as fast indicates to me that read requests can occur in parallel.
>
> So.... why doesn't the raid issue the writes in parallel? Thanks in
> advance for any help.
But it does issue writes in parallel. The problem is in the way RAID1
works. When you do a read from the RAID1, it issues one read request
to one of the underlying disks. When you do a write, it issues one write
request to _each_ of the underlying disks. So with two disks in the
mirror set, every write issued by your program causes two disk writes.
--
Chuck
"You can't read a newspaper if you can't read." --George W. Bush
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
