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SAS 712 U Series User Manual
Disabled: All write commands become asynchronous. It will ignore the
synchronous transaction demands of applications such as database or
NFS.
Standard: The default value. It depends on the applications.
Always: All write commands become synchronous even if the application
issues asynchronous transactions.
The “Sync” option will be grey out if “volume” is selected instead of file system.
This is because synchronous write function is not supported in iSCSI block access
for the time being.
TIP:
“No. of data copies” in Create File System or Volume UI is used to create
mirroring of data to avoid data corruption. When the original file corrupts, the
system will use the extra “copy” to recover the corrupt file.
The value of two means that when you copy a 10MB file, it will take up 20MB
space. The value of three means that it will take up extra double space to store
the same data in the same storage pool.
Users will not be able to see the actual extra copies. They are controlled by the
file system.
Enterprise features – Deduplication
Inline, block level redundancy remover.
Applied to both file system and volume.
Dedup function can be turned ON and OFF on the fly during I/O.
Deduplication size limit*: dedup performance is highly dependent on the size of memory.
When the size limit has reached, deduplication function on all storage pools will be disabled
automatically and grey out.
Memory size
Deduplication size limit
4GB
87GB
8GB
137GB
16GB
371GB
*
Starting from FW1.0.3, there will be deduplication size limit imposed on enabling deduplication to
avoid performance degradation.
Deduplication size limit can be removed by the following means :
。
Per pool basis. Add read cache (L2ARC) using SSD drives provided by JetStor
Technology.
。
Per system basis. Add more memory to the system or delete deduplicated data to
release space.
Summary of Contents for SAS 712U
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