Novell Open Enterprise Server 2 Manuale Utente
Optimizing Disk and Cache Performance for Traditional Volumes
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7.3.2 Change Disk and Directory Caching for Faster Writes
Change the Disk and Directory Caching parameter for faster writes if network users frequently
make many small write requests and the server is slow to respond to the requests. Use “
make many small write requests and the server is slow to respond to the requests. Use “
” in the
to modify the following parameters:
Increase the value of the Dirty Disk Cache Delay Time parameter.
This parameter specifies how long the system waits before writing a not-completely-dirty
cache buffer to disk.
cache buffer to disk.
If the value is low, the system writes to disk more frequently, but writes fewer requests each
time. If the value is high, the system waits longer before writing to disk, but executes more
write requests with each operation. A higher value provides greater efficiency in writing to
disk.
time. If the value is high, the system waits longer before writing to disk, but executes more
write requests with each operation. A higher value provides greater efficiency in writing to
disk.
If the parameter is currently at the default value of 3.3 seconds, try increasing the value to 7
seconds.
seconds.
Increase the value of the Dirty Directory Cache Delay Time parameter.
This parameter specifies how long the system keeps a directory table write request in memory
before writing it to disk.
This parameter specifies how long the system keeps a directory table write request in memory
before writing it to disk.
IMPORTANT: Increasing the parameter provides slightly faster performance, but can increase
the chance of directory tables becoming corrupted.
the chance of directory tables becoming corrupted.
If the parameter is currently at the default value of 0.5 seconds, try increasing the value to 2
seconds.
seconds.
Increase the value of the Maximum Concurrent Directory Cache Writes parameter.
This parameter determines how many write requests from directory cache buffers are executed
at one time. Increasing this value increases the efficiency of directory cache write requests.
Increasing the number of concurrent directory cache writes decreases the speed of directory
cache reads. Balance the speed of writes and reads to meet the needs or your users.
If the parameter is currently at the default value of 10, try increasing the value to 25. The
changed value is now persistent.
This parameter determines how many write requests from directory cache buffers are executed
at one time. Increasing this value increases the efficiency of directory cache write requests.
Increasing the number of concurrent directory cache writes decreases the speed of directory
cache reads. Balance the speed of writes and reads to meet the needs or your users.
If the parameter is currently at the default value of 10, try increasing the value to 25. The
changed value is now persistent.
7.3.3 Turn Off Read-After-Write Verification
Read-after-write verification is almost always provided by the hard disk. If your hard disk provides
read-after-write verification, you might want to disable the software version of read-after-write
verification in order to nearly double the speed of disk writes.
read-after-write verification, you might want to disable the software version of read-after-write
verification in order to nearly double the speed of disk writes.
WARNING: Turning off read-after-write verification can increase the risk of data corruption on the
server’s hard disk. You should use the following procedure only if your disks provide read-after-
write verification and are reliable, or if your disk subsystem provides data fault tolerance through
mirroring.
server’s hard disk. You should use the following procedure only if your disks provide read-after-
write verification and are reliable, or if your disk subsystem provides data fault tolerance through
mirroring.
Prerequisite
Hard disks that provide their own means of read-after-write verification.