[Sunhelp] SSA 112

[Bjrn Ramqvist]

Christopher J Ceska wrote:
> 
> hello,
> 
> we just picked up a Sparc Storage Array 112 with 30 1gig drives.  I was
> looking for some info on this unit.  Also the max drive capacity, and what
> kind of sbus interface card is available.  the unit came with no software so
> I am looking for a clue there too.

The SPARCstorage Array 112 is a JBOD-style diskbox, which means you are
forced to use software-based RAID/striping/mirroring. It is fitted with
a 110 MHz MicroSPARC-II chip, just like the SPARCstation 4/5-110,
coupled to a 25 MB/s FibreChannel interface and 6 (six) Fast-Wide
SCSI-II channels.
It can handle a maximum of 8 GB drives.

The good part is the number of channels internally to the disks. With
six channels you can spread I/O very rapidly among the drives and can
get good performance numbers using pure striping. The fiber interface
could be useful in situations where you want an array on another
location, another building/room/whatever, ie for security in case
emergency.
The channels are divided like this;

+-----+ +-----+ +-----+  Back
|     | |     | |     |
|  1  | |  3  | |  5  |
|     | |     | |     |
+-----+ +-----+ +-----+
|     | |     | |     |
|  2  | |  4  | |  6  |
|     | |     | |     |
+-----+ +-----+ +-----+  Front

The sad part about this beast is first of all the FibreChannel. When the
array came out on the market you could almost max out the FC with 1 GB
drives, but with faster drives and lower access-times, the 25 MB/s
barrier gets easily overcrowded. This is contrast to todays
FibreChannel, which has a maximum throughput of 100 MB/s. These two
standards are not compatible with eachother - you cannot form "SANs",
Arbitrated Loops, FC-Switching or anything, just run SCSI-protocol over
the fiber.
Second thing is the "just JBOD" feature. This means you have to put all
the stress on the host running the array, which means you need a pretty
fast host to run this baby. On SS1000E's with 85MHz SuperSPARC-II's it's
almost painful running RAID-5. Pure RAID-0 (striping w/o parity) would
probably be faster.
So, an Ultra-1 or similar would do the job more efficient.

On the host-side you need a Sun X1057A Fibre Channel controller with
either one or two FC/OMs (Fibre Channel Optical Modules). With this you
could either run two arrays on one controller, or run as a High
Availability Cluster using two machines and two arrays. The array itself
can't make use of the second channel in the same way as the
host-controller. Only one channel at a time.

Drivers for the array and hostcontroller is included with both Solaris
and Linux, although you need Disksuite or similiar on Solaris to use
striping. "ssaadm" and "luxadm" is the tools to configure the array.
Linux support is pretty stable, and with the built-in striping-support
it makes this a little bit easier.
(I have no idea about performance using this combination)

Some info;

The SPARCstorage Array 100-series is based on a 40MHz (or was it 50?)
MicroSPARC, like the SPARCstation LX, and the 110-series is based on
110MHz SPARCstation 4/5-style CPU.
The last digit in the model number is just a marketing number,
indicating drive capacity from factory. ie "model 102" would mean 2 GB
drives, "model 114" would mean 4 GB drives and so on.
The array can handle upto 9 GB drives, although only 8 GB is useful. (I
know atleast one Sun engineer that can verify this)


Hope this helps.

	/Regards, Bjorn