Sun Microsystems StorEdge 3000 Series, Руководство по лучшим практикам

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Chapter 2 Underlying Concepts and Practices 13
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Transaction-based and database update applications read and write small files in
random order.
Since the cache block size works in conjunction with the default stripe size set by the
cache optimization mode for each logical drive you create, these default stripe sizes
are consistent with the cache block size setting. You can, however, specify a different
stripe size for any logical drive at the time you create it.
Once logical drives are created, you cannot use the RAID firmware’s “Optimization
for Random I/O” or “Optimization for Sequential I/O” menu option to change the
optimization mode without deleting all logical drives. You can, however, use Sun
StorEdge Configuration Service or the Sun StorEdge CLI
set cache-parameters
command to change the optimization mode while logical drives exist. Refer to the
“Upgrading the Configuration” chapter of the
Sun StorEdge 3000 Family Configuration
Service User’s Guide and the Sun StorEdge 3000 Family CLI 2.0 User’s Guide for more
information.
Depending on the optimization mode and RAID level selected, newly created logical
drives are configured with the default stripe sizes shown in
TABLE 2-5
.
When you create a logical drive, you can replace the default stripe size with one that
better suits your application.
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For sequential optimization, available stripe size choices include 16 Kbyte, 32
Kbyte, 64 Kbyte, 128 Kbyte, and 256 Kbyte.
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For random optimization, available stripe size choices include 4 Kbyte, 8
Kbyte, 16 Kbyte, 32 Kbyte, 64 Kbyte, 128 Kbyte, and 256 Kbyte.
Once the stripe size is selected and data is written to logical drives, the only way to
change the stripe size of an individual logical drive is to back up all its data to
another location, delete the logical drive, and create a logical drive with the stripe
size that you want.
TABLE 2-5
Default Stripe Size Per Optimization Mode (Kbyte)
RAID Level Sequential I/O Random I/O
0, 1, 5 128 32
3 16 4