G A L A X Y ® A U R O U R A L S C O N F I G U R A T I O N A N D S Y S T E M I N T E G R A T I O N G U I D E
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Section 3 Management
lower gives up some of the cache to the non-real-time users. It's almost the opposite of above.
Note that this setting applies globally to all real-time users.
Max Data Rate of Non-Real-Time Requests (MB/SEC) 0 for no limit:
This allows you to
limit the bandwidth of non-real-time users in megabytes per second. It is used to free up
bandwidth for real-time users as well. The value entered here is in megabytes per second.
The default value, 0, does not limit the maximum data rate for non-real-time users.
Max Number of Non-Real-Time Requests:
Another way of limiting non-real-time users is to
limit the amount of read/write commands they can send. Note that this setting affects all non-
real-time users. The default value is 4. Setting the value lower would further limit non-real-time
users. Setting it higher would cache more requests.
Reconstruct in Advance of Drive Completion:
If a drive isn’t performing as well as the rest,
this option is used to base the data on the parity, instead of the data returned from the drive. In
many cases, this can compensate for a slow drive. This option is disabled by default.
Reconstruction Priority (from 0 to 100):
The array is capable of reconstructing while it is
being used. This value controls the balance of priority given to reconstruction versus the data
access. The default value is 0, which means reconstruction is only performed when the array
is idle. If you set it to 100 (which is definitely not recommended), the array would run very
slowly to the clients, while reconstructing at full speed. So as an example, consider a value of
10 - This would mean that the array would spend 10% of it's time while being accessed, doing
reconstruction. The value is up to you - the more time and/or speed you can sacrifice while the
array is being used to reconstruction, the faster the reconstruct will complete.
Enable PQ Verification:
Default is No. This value is a form of error-detection and correction
(Raid-6 only). If this value is enabled, while the array is reading, it will compare the data read
against the two parity generators - there has to be a 3-way match between the data and each
of the two parity generators. If there isn't, the data from the parity generators is used instead of
the data from the drive in question - this substitution is made in real-time. So basically, if the
array detects something wrong in the data, it corrects it. Enabling this option might affect read
transfer rates.
Internal Diagnostic Message Level:
More explicitly, this value determines what you want the
internal diagnostics to log. Here are the values and what they do:
Disabled
Do not log anything.
Requests
Only log read/write requests.
State Started
Only log state engine starts.
State Ended
Only log state engine completions.
BIO Started
Only log Block I/O starts.
BIO Ended
Only log Block I/O completions.
Cache Monitor the cache.
Debug Monitor debugging.
Performance
Monitor performance.
Target Monitor targets.
Silent Data Corruption Monitor for the problem described under PQ Verification.
