RAID Technology
105
Figure 19. Dynamic Sparing and Correction
Dynamic sparing is a method of removing a drive from service if its
read/write errors exceed a certain threshold value. On normal read and
write operations, the array keeps track of the number of errors that occur. If
the error threshold is reached, the system considers that the drive is likely to
cause an unrecoverable error and automatically copies the data from that
drive to a spare disk. The dynamic sparing method used in the XP512 is the
same for both RAID0/1 and RAID5.
Correction copy is invoked when the system encounters an unrecoverable
error occurring on a drive. In RAID5, correction copy will regenerate the
original data for that drive using the data from the other two drives and the
parity data, and then the controller copies the regenerated data onto the
spare disk. In RAID0/1, correction copy just has to copy the data from the
mirrored disk onto the spare disk. After a failed disk has been replaced, the
data is moved back to its original location, and the spare disk is then
available as an active spare.
DKC
Disk 1
Disk 2
Disk 3
Disk 4
Ready to accept
I/O requests
Ready to accept
I/O requests
Ready to accept
I/O requests
DKC (RAID5)
Disk 1
Disk 2
Disk 3
Disk 4
Spare
disk
Spare
disk
Spare
disk
RAID 5
DKC (RAID 0/1)
Disk 1
Disk 2
Disk 3
Disk 4
RAID 0/1
Содержание StorageWorks XP48 - Disk Array
Страница 1: ...HP SureStore E Disk Array XP512 HP SureStore E Disk Array XP48 H Owner s Guide ...
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Страница 56: ...56 HP SureStore E Disk Array XP512 XP48 Owner s Guide Figure 10 Pulling the UNIT EMERGENCY POWER OFF Switch ...
Страница 69: ...The HP SureStore E Disk Array XP Family of Optional Software 69 Figure 11 Remote Control XP Menus ...
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Страница 86: ...86 HP SureStore E Disk Array XP512 XP48 Owner s Guide VCCI EMC Statement Japan ...
Страница 87: ...Regulatory Statements 87 BSMI EMC License Number and Statement Taiwan XP512 XP48 ...
Страница 88: ...88 HP SureStore E Disk Array XP512 XP48 Owner s Guide Harmonics Conformance Japan ...
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