Ciprico 4400 user manual Restore the backup

MediaVault 4440 User Manual ProblemSolving

TABLE 7-2.Frequently Asked Questions.

What is RAID 6?	As in RAID 5, RAID 6 staggers its parity information across
	multiple drives. Its major difference, however, is that it writes
	two parity blocks for every stripe of data, which means that the
	array is capable of remaining accessible to the users even
	after having sustained two simultaneous drive failures. The
	advantage of a RAID 6 array versus a RAID 5 array with a hot
	spare risk is that no rebuilding is necessary to bring the last
	disk into the array in the event of a failure. In this sense,
	performance is more or less guaranteed after a single disk
	failure under RAID 6, whereas a significant performance hit
	occurs during the rebuilding required under RAID 5.
	RAID 6's parity scheme is not simply multiple copies of the
	same parity information, but rather two different means of cal-
	culating parity information for the same data. This results in a
	much higher computing overhead than the already-intensive
	RAID 5 scheme, and a resulting increase in controller/CPU
	usage. This requirement for the second parity calculation and
	write, however, further adversely impacts the write perfor-
	mance of a RAID 6 array versus a RAID 5 solution.
	RAID 6 is an excellent choice for both extremely mission-
	critical applications and in instances where large numbers of
	disks are intended to be used in the array to improve read
	performance.
What is the self-healing feature I've heard	This is a new name given to a slightly new technique for
about?	relocating bad sectors on the disks. Rather than relocate the
	actual sector, a pointer for the sector number is used.
	When a bad sector is found, the pointer updates to skip that
	area - this is done while the drive is reading/writing. If you
	were to watch the performance of this bad sector, as the
	performance appears to increase, it could be said the sector
	was "cured."
Do I need to do any software-based	No. Programs, such as Disk First Aid, Scan Disk, etc. are not
preventative maintenance on the array	recommended
How do I defragment the array?	Defragmenting software is not recommended. The best way to
	defragment the array is to back it up, reformat/restripe it, then
	restore the backup.

MV 4440_Ciprico Inc. 7-5