Ldev Striping Across Array Groups - Hitachi Virtual Storage Platform G1000 Hardware Manual
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- User manual (40 pages)
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Description
Advantage
Disadvantage
LDEV striping across array groups
In addition to the conventional concatenation of RAID 1 array groups (4D
+4D), the storage system supports LDEV striping across multiple RAID 5
array groups for improved logical unit performance in open-system
environments. The advantages of LDEV striping are:
• Improved performance, especially of an individual logical unit, due to an
increase in the number of drives that constitute an array group.
• Superior workload distribution: If the workload of one array group is
higher than another array group, you can distribute the workload by
combining the array groups, thereby reducing the total workload
concentrated on each specific array group.
The supported LDEV striping configurations are:
• LDEV striping across two RAID5 (7D+1P) array groups. The maximum
number of LDEVs in this configuration is 1000. See the following figure.
• LDEV striping across four RAID5 (7D+1P) array groups. The maximum
number of LDEVs in this configuration is 2000. See
Striping Across four RAID5 (7D+1P) Array Groups on page
Hitachi Virtual Storage Platform G1000, G1500, and Virtual Storage Platform F1500 Hardware Guide
Item
Data blocks are scattered to multiple disks in the same way as RAID 5 and two
parity disks, P and Q, are set in each row. Therefore, data can be assured even
when failures occur in up to two disk drives in a parity group.
RAID 6 is much more reliable than RAID 1 and RAID 5 because it can restore
data even when failures occur in up to two disks in a parity group.
The parity data P and Q must be updated when data is updated, RAID 6
imposes a write heavier than that on RAID 5. Performance of the random
writing is lower than RAID 5 when the number of drives makes a bottleneck.
Hardware architecture
Description
Figure 12 LDEV
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