[Fedora-sparc] SATA support on an Ultra 5 system

[Patrick Ale]

On Mon, Mar 8, 2010 at 5:17 AM, Jon Masters <jonathan at jonmasters.org> wrote:

> I recommend this approach. The SATA disk is drastically faster than the
> original very legacy IDE on the Ultra 5. The use of a flash disk is very
> reliable (in theory, anyway) and I can even use eSATA if I want to, or
> the faster IDE or SATA ports on the SATA PCI upgrade card.

Hi, I can provide you some troughput statistics that will hopefully
show you a bit what to expect.
SATA indeed gives you a lot of speed but there are some things to
consider and not get your hopes up too much.


My system:
- Ultra 5, 440Mh CPU, 512MB RAM.

sda: Maxtor 80GB ATA drive connected to c0t0 (internal IDE controler).
The internal IDE controller goes up to MWDMA2, which gves you around
16MB/s according to the standards.

sda: multi word DMA 2 (16MB/s) (EXT3 filesystem)
[root at medusa slowdrive]# dd if=/dev/zero of=myfile.txt bs=4096 count=250000
250000+0 records in
250000+0 records out
1024000000 bytes (1.0 GB) copied, 61.2546 s, 16.7 MB/s

sda: multi word DMA 2 (16MB/s) with RAID1 layer
[root at medusa mnt]# dd if=/dev/zero of=myfile.txt bs=4096 count=250000
250000+0 records in
250000+0 records out
1024000000 bytes (1.0 GB) copied, 62.3785 s, 16.4 MB/s

sda: multi word DMA 2 (16MB/s) with RAID1 layer and LVM layer
[root at medusa mnt]# dd if=/dev/zero of=myfile.txt bs=4096 count=250000
250000+0 records in
250000+0 records out
1024000000 bytes (1.0 GB) copied, 63.119 s, 16.2 MB/s


What you can see above is that your performance bottleneck is the IDE
bus with the poor MWDMA2 capabilities.
However, whatever you decide to do, RAID, LVM or RAID + LVM, you will
always get the full speed.



sdc: Maxtor 1TB SATA disc connected to a Silicon Image 3512 PCI card.
The kernel configured this with UDMA100 (100MB/s)

sdc: Ultra DMA 100 (with EXT3 FS)
[root at medusa /]# dd if=/dev/zero of=myfile.txt bs=4096 count=250000
250000+0 records in
250000+0 records out
1024000000 bytes (1.0 GB) copied, 23.9389 s, 42.8 MB/s


sdb: Maxtor 1TB SATA disc connected t a Silicon Image 3512 PCI card.
The kernel configured this with UDMA100 (100MB/s)

sdb: Ultra DMA 100 with RAID 1 layer
[root at medusa mnt]#  dd if=/dev/zero of=myfile.txt bs=4096 count=250000
250000+0 records in
250000+0 records out
1024000000 bytes (1.0 GB) copied, 39.9939 s, 25.6 MB/s

sdb: Ultra DMA 100 with LVM layer
[root at medusa mnt]# dd if=/dev/zero of=myfile.txt bs=4096 count=250000
250000+0 records in
250000+0 records out
1024000000 bytes (1.0 GB) copied, 35.3786 s, 28.9 MB/s


sdb: Ultra DMA 100 with RAID 1 and LVM layer
[root at medusa mnt]# dd if=/dev/zero of=myfile.txt bs=4096 count=250000
250000+0 records in
250000+0 records out
1024000000 bytes (1.0 GB) copied, 38.5377 s, 26.6 MB/s


Above shows that when you use SATA on an Ultra 5 you get way better
speeds than with your IDE disc but not what you would get on a faster
sparc.
My guess is that eventhough you use UDMA, the troughput is just to
much for the CPU. This becomes more clear when you use RAID or LVM
volumes, where you can see a decrease of 20MB/s when either RAID or
LVM is used.
Also keep in mind that these tests were from /dev/zero to the
filesystem. An rsync from sdb to sdc (SATA to SATA) was very
disapointing.


Still LVM/RAID on SATA will give you a better performance than when
you use IDE just don't expect wonders. An rsync from sdb to sdc for
example went with 320KB/s...



Patrick