HSG80 ACS Solution Software Version 8.7 for Compaq Tru64 UNIX Installation and Configuration Guide

Table Of Contents
Planning Storage Configurations
2–20 HSG80 ACS Solution Software Version 8.7 for Compaq Tru64 UNIX Installation and
Configuration Guide
Striping does not protect against data loss. In fact, because the failure of one
member is equivalent to the failure of the entire stripeset, the likelihood of losing
data is higher for a stripeset than for a single disk drive.
For example, if the mean time between failures (MTBF) for a single disk is l hour,
then the MTBF for a stripeset that comprises N such disks is l/N hours. As another
example, if the MTBF of a a single disk is 150,000 hours (about 17 years), a
stripeset comprising four of these disks would only have an MTBF of slightly
more than 4 years.
For this reason, you should avoid using a stripeset to store critical data. Stripesets
are more suitable for storing data that can be reproduced easily or whose loss does
not prevent the system from supporting its critical mission.
Evenly distribute the members across the device ports to balance the load and
provide multiple paths.
Stripesets may contain between two and 24 members.
If you plan to use mirror members to replace failing drives, then create the original
stripeset as a stripeset of 1-member mirrorsets.
Stripesets are well-suited for the following applications:
Storing program image libraries or run-time libraries for rapid loading.
Storing large tables or other structures of read-only data for rapid application
access.
Collecting data from external sources at very high data transfer rates.
Stripesets are not well-suited for the following applications:
A storage solution for data that cannot be easily reproduced or for data that
must be available for system operation.
Applications that make requests for small amounts of sequentially located
data.
Applications that make synchronous random requests for small amounts of
data.
Spread the member drives as evenly as possible across the six I/O device ports.