Technical Bulletin #18
To: All Sites Using SPARCstorage Arrays
From: Customer Support
Date: 09-Oct-1996
Subject: Technical Bulletin #18
- Preventing Data Loss with SPARCstorage Arrays
-
- Performance Improvements for SPARCstorage Arrays
-
- Any Questions?
Preventing Data Loss with SPARCstorage Arrays
Rational
Engineering is aware of two problems with SPARCstorage Arrays that
can cause data loss:
- If your site uses SPARCstorage Arrays as VOB servers, you must
obtain Sun ECO A0081-1. As with other seek-intensive database
programs, ClearCase VOB processes combined with an array of
high-speed disks can result in excessive vibration, leading to
head crashes and other disk failures. ECO A0081-1 addresses this
problem by providing a means of damping these vibrations. Check
with your Sun SR/SE to make sure your SSA has this ECO kit
installed. Sun is exploring other options to eliminate these
problems with SPARCstorage Arrays.
- At this date, Sun Microsystems does not support using their
Prestoserve products on systems with a SPARCstorage Array with
Fast Writes enabled as this can cause data loss. Check with your
Sun SR/SE regarding infodoc 13420, which discusses this
topic.
ClearCase customers must conform to these two
requirements. If data loss occurs from failure to do so, Rational
reserves the right to charge for its services in reconstructing your
data.
Performance Improvements for SPARCstorage Arrays
Rational
Engineering suggests the following choices to improve ClearCase
performance on SPARCstorage Arrays:
- Enable Fast Writes to improve VOB server I/O performances.
Fast Writes are disabled by default. Fast Writes are not supported
with Prestoserve.
- Do not use RAID Level 5, as write performance is very slow.
- Use RAID Level 0 + 1 for the best combination of performance
and availability. RAID Level 0 (striping) helps with I/O
performance, while RAID Level 1 (mirroring) provides higher
availability. You can also choose either Level 0 or Level 1
independently.
Any Questions?
If you have any questions regarding the situations discussed in this Technical Bulletin, please contact Customer Support at support@rational.com or (781) 676-2450 in Massachusetts or 31-23-569-4310 in the Netherlands.