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Copyright@2004~2014 Qsan Technology, Inc. All Rights Reserved.
Qsan Document – User Manual
Sometimes, rebuild is called recover; they are the same meaning. This table describes the
relationship between RAID levels and recovery.
Operation
Description
RAID 0
Disk striping. No protection for data. RAID group fails if any hard drive fails
or unplugs.
RAID 1
Disk mirroring over 2 disks. RAID 1 allows one hard drive fails or
unplugging. Need one new hard drive to insert to the system and rebuild
to be completed.
N-way mirror
Extension to RAID 1 level. It has N copies of the disk. N-way mirror allows
N-1 hard drives failure or unplugging.
RAID 3
Striping with parity on the dedicated disk. RAID 3 allows one hard drive
failure or unplugging.
RAID 5
Striping with interspersed parity over the member disks. RAID 5 allows one
hard drive failure or unplugging.
RAID 6
2-dimensional parity protection over the member disks. RAID 6 allows two
hard drives failure or unplugging. If it needs to rebuild two hard drives at
the same time, it will rebuild the first one, then the other in sequence.
RAID 0+1
Mirroring of RAID 0 volumes. RAID 0+1 allows two hard drive failures or
unplugging, but at the same array.
RAID 10
Striping over the member of RAID 1 volumes. RAID 10 allows two hard
drive failure or unplugging, but in different arrays.
RAID 30
Striping over the member of RAID 3 volumes. RAID 30 allows two hard
drive failure or unplugging, but in different arrays.
RAID 50
Striping over the member of RAID 5 volumes. RAID 50 allows two hard
drive failures or unplugging, but in different arrays.
RAID 60
Striping over the member of RAID 6 volumes. RAID 60 allows four hard
drive failures or unplugging, every two in different arrays.
JBOD
The abbreviation of “Just a Bunch Of Disks”. No data protection. RG fails if
any hard drive failures or unplugs.
Migrate and Move RAID Groups
Migrate RAID Level
function changes the RAID group to different RAID level or adds the member
disks of the RAID group for larger capacity. Usually, the RAID group migrates to higher RAID level
for better protection. To do migration, the total size of RAID group must be larger than or equal to
the original RAID group. The limitation is that it’s not allowed expanding the same RAID level with
the same physical disks of the original RAID group. There is a similar function
Move RAID Level
which will move the member disks of the RAID group to totally different physical disks. In addition,
thin provision RAID group cannot execute migrate or move, it uses
Add RAID Set
to enlarge
capacity. Describe more detail in the Thin Provision section.
