Gateway 9510 Gateway 9510 Server User Guide - Page 128

Write Policy, Write-back, Write-through, Cache Policy, Cached I/O, Direct I/O, Direct, Caution

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Configuring your ROMB RAID solution with the RAID BIOS Console configuration utility 12 Select the Write Policy from the list. Use this screen to select the write and cache policies. The write policy parameter specifies the cache write policy. You can set the write policy to Write-back or Write-through. In Write-back caching, the controller sends a data transfer completion signal to the host when the controller cache receives all the data in a transaction. In Write-through caching, the controller sends a data transfer completion signal to the host after the disk subsystem receives all the data in a transaction. Write-through caching is the default setting. Write-through caching has a data security advantage over Write-back caching. Write-back caching has a performance advantage over Write-through caching, but it should only be enabled when the optional battery backup module is installed. Caution Do not use write-back caching for any logical drive in a Novell NetWare volume. 13 Select the Cache Policy from the list. The cache policy applies to I/O on a specific logical drive. It does not affect the read ahead cache. The options are Cached I/O or Direct I/O. Cached I/O buffers all reads in cache memory. Direct I/O does not buffer reads in cache memory. When possible, Direct I/O does not override the cache policy settings. Direct I/O transfers data to cache and the host concurrently. If the same data block is read again, the host reads it from cache memory. 14 Select the Span from the list. Enable or disable the spanning mode for the current logical drive. If spanning is enabled, the logical drive can occupy space in more than one array. If spanning is disabled, the logical drive can occupy space in only one array. For two arrays to be spannable, they must have the same stripe width and must be consecutively numbered. If these criteria are not met, the utility ignores the Span setting. Spanning lets the logical drive stripe across multiple arrays. Using this option enables the use of RAID 10 and RAID 50. www.gateway.com 123

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www.gateway.com
Configuring your ROMB RAID solution with the RAID BIOS Console configuration utility
12
Select the
Write Policy
from the list.
Use this screen to select the write and cache policies. The write policy parameter
specifies the cache write policy. You can set the write policy to
Write-back
or
Write-through
. In
Write-back
caching, the controller sends a data transfer completion
signal to the host when the controller cache receives all the data in a transaction. In
Write-through
caching, the controller sends a data transfer completion signal to the
host after the disk subsystem receives all the data in a transaction.
Write-through
caching is the default setting.
Write-through
caching has a data security advantage over
Write-back
caching.
Write-back
caching has a performance advantage over
Write-through
caching, but it should only be enabled when the optional battery backup module is
installed.
13
Select the
Cache Policy
from the list.
The cache policy applies to I/O on a specific logical drive. It does not affect the read
ahead cache. The options are
Cached I/O
or
Direct I/O
.
Cached I/O
buffers all reads in
cache memory.
Direct I/O
does not buffer reads in cache memory. When possible,
Direct
I/O
does not override the cache policy settings.
Direct I/O
transfers data to cache and
the host concurrently. If the same data block is read again, the host reads it from cache
memory.
14
Select the
Span
from the list.
Enable or disable the spanning mode for the current logical drive. If spanning is
enabled, the logical drive can occupy space in more than one array. If spanning is
disabled, the logical drive can occupy space in only one array.
For two arrays to be spannable, they must have the same stripe width and must be
consecutively numbered. If these criteria are not met, the utility ignores the Span
setting.
Spanning lets the logical drive stripe across multiple arrays. Using this option enables
the use of RAID 10 and RAID 50.
Caution
Do not use write-back caching for any logical drive in a Novell
NetWare volume.