[SunRescue] disks for SPARCstarage array

[Bjrn Ramqvist]

Gregory Leblanc wrote:
> 
> > One side-note;
> > the array can't make use of drives bigger than 8.4GB, so you
> > are pretty
> > much wasting space with 18GB drives if you even consider that. (A Sun
> 
> This is a SCSI-SCSI RAID box, then?  Have you done any testing to see what
> exactly this means?  On our BRAND NEW Compaq DS20, the largest RAID array
> that we could create was 32,768MB, on a single array.  However, we could do
> this use any combination of drives that we liked, from 9GB drives, up to
> 18GB drives.  So, is this box limited to a total of 30 9GB drives, or is it
> limited to a total of 252GB, which could be about 15 18GB drives?

The SPARCstorage Array 100 and 110 has a limit (due to some sort of
prom?) of 8GB/drive. That's what the Sun-engineer told me last time we
picked these up. Oh, you'd better not compare these to a pure RAID-box,
since they have often all the RAID-related algorithms inside, into
hardware, so they are much faster.
This box is a so-called "JBOD" (Just-a-Bunch-Of-Disks) array, which
means you have to do all the striping/mirroring/parity calculations in
software on the host. This can be a performance limiting factor, so be
sure to put it on a descent host if you need some speed.

In theory, the 6 Fast-Wide SCSI-channels max out at 20MB/s. That's a
pretty descent speed since you distribute the load fairly among the
drive. The limiting factor here is the FC-port, which stops at 25MB/s
(250mbps). That would sure be a limiting factor, considering the speed
of todays 9GB drives. So basic fact is that this is a "SCSI-SCSI" box,
just that the SCSI-signal travels through the Fibre-Channel protocol via
fiber between the host and the array.

What kind of Compaq Array are you running?
I know our FC-AL (1Gbps) Compaq RAIDarray 8000 have 2 RAIDsets with
6x36GB which makes 180GB RAID3/5 storage.
Ofcourse hardwarebased.
Don't forget that the SPARCstorage Array is somewhat old nowadays. Many
techniques has been fine-tuned since the first arrival in -94.

> > Greg, feel free to take notes into the HW-ref
> 
> Yep, the info is getting filed, thanks.  Maybe I'll just have to write some
> random snippits for now...
>         Greg
> 
> P.S.  I'm assuming that info here is pretty much PD, since it's going to a
> mailing list...

I sure hope so. It would be a waste to see all the info floating around
goes to waste.


	/Regards, Bjorn