G A L A X Y ® A U R O U R A 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
3.1.2
RAID Creation, Status, and other RAID configuration information
Although you have RAID created already you will need to know how to create
a RAID (In this case, the example used is when no RAID exists):
Do not click the Create button until everything else on the row is set correctly.
To the right of the create button is where you give the RAID a unique name.
The RAID requires a unique name, because it is referenced in a lot of places
within Aurora, and would not be easy to identify if there was more than one
RAID with the same name.
The next setting is the cache size. Cache is a designated part of the RAM in
the array, used to hold data while waiting to go to the drives, or coming from
the drives, waiting for the host. It is used to increase speed, because
compared to the speed of the RAM, the speed of the drives are relatively slow,
and the speed going to the host computer itself is unpredictable.
Important: The cache size selected is directly subtracted from the RAM
in the array, so care must be taken so that not all of the RAM is not used
up. For example, if you have 6GB of RAM, and already have an RAID
defined which has a cache size of 4GB, then you don't have enough free
RAM to create another RAID. Also, assume the operating system of the
array itself takes about 2GB of RAM. In general, a larger cache yields
greater performance. Once you know what cache size you would like to
use, select it by left-clicking on the down arrow under Cache Size, then
scroll down to the size that you would like, and left-click on it.
The next setting is the RAID level – it can be RAID 0 or RAID 6. With RAID 0,
you get the capacity and potential speed of all of the disks, however if a single
drive fails, you will lose access to all of your data. With RAID 6, you lose
capacity equivalent to two of the drives, and get nearly the same speed,
however up to two drives can fail and your data will still be accessible and at
full speed.
The next setting is the number of the first slot/device to use for the RAID. Use
the device count, where you would select the number of slots/drives to use in
the RAID. The numbers used for the starting slot and device count must be