Bug#351929: FWD: (Severe?) Performance issues with ext3 created on RAID5 with partman
On Wed, Feb 08, 2006 at 10:35:32AM -0500, Joey Hess wrote:
> Package: partman-ext3
> Severity: important
>
> ----- Forwarded message from Leo Bogert <spam-goes-to-dev-null@gmx.net> -----
>
> From: Leo Bogert <spam-goes-to-dev-null@gmx.net>
> Date: Wed, 8 Feb 2006 08:02:30 +0100
> To: debian-boot@lists.debian.org
> Subject: (Severe?) Performance issues with ext3 created on RAID5 with partman
> X-Mailer: Microsoft Office Outlook, Build 11.0.6353
>
> Hello,
>
> I recently installed the following system:
> Celeron 2800 MHz 64 bit, running on an ICH7 board.
> 2 GB RAM
> [3x 300GB SATA] <=> [sofware RAID5] <=> [loop-AES encryption] <=> [ext3fs]
> running on Debian-amd64 testing, kernel 2.6.15.2
>
> I created the RAID5 and ext3fs using the Debian installer.
> Now my problem is: The read speed from the harddisks does not go over
> exactly 51 MB/s. (mesured several times with different files by dd
> if=/some-large-file of=/dev/zero)
> When doing dd if=/dev/md1 of=/zev/zero I get almost exactly 100 MB/s though,
> I also tried that with different offsets.
> So the read speed of the RAID5 without any overhead added is 100 MB/s.
> Now of course, one would first assume that the encryption is the bottleneck
> because it uses much CPU power.
> But I used /dev/shm to benchmark loop-AES also and it was at 270 MB/s.
50M/s on one drive. 3 disk raid5 is 2 data + 1 parity setup, so read
should be 2 * 50M/s = 100M/s. Looks sane to me. What speed was it
expected to run at? Certainly not 150M/s since that would be the read
speed including the parity data.
I see no indication of any bottlenecks. I am actually impressed it runs
that efficiently.
Len Sorensen
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