Hitachi AMS2100 User Manual page 64

Table 2-2: P-VOL and Data Pool RAID Configuration
P-VOL
RAID 1+0
(N = 1 to 8)
RAID 1+0
(N = 1 to 8)
RAID 5 (N = 4) (see
Note 1)
RAID 5 (When N = 4)
(see Note 1)
RAID 5 (When N = 8)
(see Note 1)
RAID 6 (When N = 4)
(see Note 2)
RAID 6 (When N = 8)
(see Note 2)
RAID 6 (When N = 4)
(see Note 2)
2-12
Hitachi AMS 2000 Family Copy-on-Write SnapShot User Guide
•
Data Pool
RAID 1+0
(N = 1 to 8)
RAID 5 (N = 4) (see
Note 1)
RAID 1+0 (N = 1 to 8)
RAID 5 (When N = 4)
(see Note 1)
RAID 5 (When N = 8)
(see Note 1)
RAID 6 (When N = 4)
(see Note 2)
RAID 6 (When N = 8)
(see Note 2)
RAID 5 (When N = 4)
(see Note 1)
Note 1: Capacity = (1+1/N) where N = Number of data drives in
RAID
Note 2: Capacity = (1+2/N) where N = Number of data drives in
RAID
• RAID 5 (4D+1)/RAID 5 (4D+1) is the recommended
configuration because 4D+1P is a recommended configuration
for performance. It is also a balanced ratio of redundancy and
user data related to RAID 5.
• When two or more command devices are located in the same
AMS array, assign them to respective RAID groups. This
safeguards the SnapShot system in the event of system
malfunction, in which case both command devices would
become unavailable.
• When two Differential Management LUs are located in the
same AMS array, assign them to respective RAID groups. This
safeguards the SnapShot system in the event of system
malfunction, in which case both DM-LUs would become
unavailable.
Planning and design
Amount of Total Amount of
User Data SnapShot
1 4
1 2+1.25 = 3.25
1 1.25+2 = 3.25
1 1.25+1.25 = 2.5
1 1.125+1.125 =
2.25
1 1.5+1.5 = 3
1 1.25+1.25 = 2.5
1 1.5+1.25 = 2.75
Share of User
Data
¼
1/3.25
1/3.25
1/2.5
1/2.25
1/3
1/2.5
1/2.75