Re: RAID stripe size question

On 8/3/06, Luke Lonergan <LLonergan(at)greenplum(dot)com> wrote:
> Merlin,
>
> > moving a gigabyte around/sec on the server, attached or no,
> > is pretty heavy lifting on x86 hardware.

> Maybe so, but we're doing 2GB/s plus on Sun/Thumper with software RAID
> and 36 disks and 1GB/s on a HW RAID with 16 disks, all SATA.

that is pretty amazing, that works out to 55 mb/sec/drive, close to
theoretical maximums. are you using pci-e sata controller and raptors
im guessing? this is doubly impressive if we are talking raid 5 here.
do you find that software raid is generally better than hardware at
the highend? how much does this tax the cpu?

> WRT seek performance, we're doing 2500 seeks per second on the
> Sun/Thumper on 36 disks. You might do better with 15K RPM disks and
> great controllers, but I haven't seen it reported yet.

thats pretty amazing too. only a highly optimized raid system can
pull this off.

> BTW - I'm curious about the HP P600 SAS host based RAID controller - it
> has very good specs, but is the Linux driver solid?

have no clue. i sure hope i dont go through the same headaches as
with ibm scsi drivers (rebranded adaptec btw). sas looks really
promising however. the adaptec sas gear is so cheap it might be worth
it to just buy some and see what it can do.

merlin