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Initialization Method
:
Initialization of a disk sets all data bits to 0, essentially
clearing all the data on the drive. It is important to initialize disks as previous data
physically stored on the drive may interfere with new data.
•
Keep Old Data
: This option skips the initialization process and all data on each
physical disk of the array will be untouched.
•
Quick Init:
This option grants immediate access to the RAID array by skipping
the initialization process, but it will delete all data.
Note
:
Skipping initialization
is generally not recommended as residual data on disks may interfere with new
data in the future.
•
Foreground
: The array initialization process will be set at high priority. During
this time array is not accessible, but the initialization process will complete
much faster.
•
Background
: The array initialization process will have a lower priority. During
this time the array will be accessible, but the initialization process will take
much longer to complete.
Note 1
: Initializing takes a significant amount of time (approximately 2 hours per one
TB).
Background and Foreground Initialization
Fully initializing the array will completely zero out the data on the disks, meaning the
disk will be completely wiped and every bit on the disk will be set to 0. Foregoing
initialization means the array will still be created, and you can still write new data onto
the array. But when your array requires rebuilding, residual data left behind may
interfere with the process.
Cache Policy (Default: Write Back)
Write Back
–
Any data written to the array will be stored as cache, resulting in better
I/O performance at the risk of data failures due to power outages. Data will be stored
as cache before it is physically written to the disk; when a power outage occurs, any
data in the cache will be lost.
Write Through
–
Data written to an array is directly written onto the disk, meaning
lower write performance for higher data availability. Without cache acting as a buffer,
write performance will be noticeably slower but data loss due to power outages or other
failures is significantly minimized.
Block Size (default: 512K)
Adjusting the block size towards your disk usage can result in some performance gain.
In a typical RAID configuration, data of the virtual drive is striped (or spread across)
the physical drives. Having a smaller array block size will increase the likelihood of
accessing all physical drives when processing large I/O requests. Multiple physical
drives working in parallel increases the throughput, meaning better performance.
For smaller I/O requests (512 bytes to 4 kilobytes), it is better to have each individual
disks handle their own I/O request, improving the IOPS (I/O per second), rather than
having one tiny I/O request being handled by multiple disks.
