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65
U Series User Manual
3.
Use the drop-down list to select a Pool.
4.
Select Type, Property and No. of data copies.
5.
Enter the Size for the file system or volume.
6.
Click OK button.
TIP: “Type” has two options – “File system” and “Volume”.
File system: File level access and folder sharing. To use with data services such
as CIFS, NFS, AFP, FTP, and WebDAV.
Volume: Block level access. To use with iSCSI target function.
TIP: “Sync” means synchronous I/O, which is similar to the definition of write-
through. Synchronous I/O is that every file system transaction is written and
flushed to stable storage devices by a system call return. The application needs
to wait for the physical data update completion before it could issue another
command. Latency will be longer and performance will suffer.
If you don’t know how to use this setting, please leave it as default.
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.