Requirements And Recommendations For Snapshot Logical Units; Raid Configuration For Lus Assigned To Snapshot - Hitachi AMS2100 User Manual
Ams 2000 family copy-on-write snapshot
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- Hardware manual (306 pages) ,
- Service manual (192 pages)
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Requirements and recommendations for SnapShot Logical
Units
RAID configuration for LUs assigned to SnapShot
2-10
Hitachi AMS 2000 Family Copy-on-Write SnapShot User Guide
•
Up to 64 volumes can be assigned to a data pool.
•
When a volume is assigned to a data pool, it is no longer
recognized by a host.
Please review the following key rules and recommendations
regarding P-VOLS, V-VOLS, and data pools. See
Specifications, for general specifications required for SnapShot.
•
Primary and secondary volumes must be set up prior to making
SnapShot copies.
•
The P-VOL and S-VOL must be assigned to the same controller.
•
Assign four or more disks to SnapShot LUs for optimal host and
copying performance.
•
Volumes used for other purposes should not be assigned as a
primary volume. If such a volume must be assigned, move as
much of the existing write workload to non-SnapShot volumes
as possible.
•
If multiple P-VOLs are located in the same drive, the status of
the pairs should stay the same (Simplex, Paired, and Split).
When status differs, performance is difficult to estimate.
Please observe the following regarding RAID levels when setting up
SnapShot pair volumes, data pools, command devices, and
Differential Management LUs.
•
More than one pair may exist on the same RAID group on the
array. However, when more than two pair are assigned to the
same group, the impact on performance increases. Therefore, it
is recommended that when creating pairs within the same RAID
group, you should standardize the controllers that control LUs in
the RAID group.
•
Performance is best when P-VOL and data pool are assigned to a
RAID group consisting of SAS drives, SAS7.2K drives, SSD
drives, or SAS (SED) drives. Performance decreases when
located on SATA drives.
•
Multiple data pool volumes can exist on a single array, but the
RAID group for each data pool volume should be restricted only
to that POOL, otherwise performance is impacted.
•
Locate a P-VOL and associated data pool in different ECC groups
within a RAID group, as shown in
the same ECC group, performance decreases and the chance of
failure increase.
Planning and design
Appendix A,
Figure
2-6. When they are in
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