Jamaica/HASS performance

[Jim Smith]

Hi,

I want to purchase a Jamaica/HASS, how do I configure it for the best performance ?

[Stefan Farrelly · Accepted solution]

Heres a list of the performance of Jamaica/HASS disks;

Disk_ProductID Size Speed(1)
========================
ST15150W 4Gb ~6.5 MB/s
ST34371W 4Gb ~8.5 MB/s
ST34572WC 4Gb ~10 MB/s
ST34573WC 4GB ~14 MB/s

ST19171 9GB ~10 MB/s
ST39173WC 9GB ~14.5 MB/s
ST39175LC 9GB ~18 MB/s
(1) using time dd if=/dev/rdsk/xxx

So for ultimate peformance make sure your Jamaica comes with the fastest disks available in the size you want. Install them using 2 SCSI controllers on your server (4 disks per controller) then create youre logical volumes striped over disks on both controllers and as many disks as possible and you will get fantastic performance.

[Jim Smith]

Hey, thanks for the fast response, exactly what I was after!

[John Palmer]

The Jamaica has 8 disk slots in two banks of 4. These are often connected together with a short SCSI cable to form a combined bus of 8 slots.

Consider configuring it as two separate SCSI busses with 4 disks on each. The FWD SCSI bus is rated at 20Mb per second so you can overload it with more than 4 disks at 5Mb per second each. This does require two SCSI controller cards per Jamaica though.

Regards,

John

[Tim Malnati]

The older Fast-wide-differential interface (20 mbs) to the Jamaica has become the limiting factor when considering performance. If your on an older box series (like a K) there is little you can do to improve it where no faster controllers are available for SCSI.