Hitachi AMS 2000 User Manual page 95

Table 5-2: TCE Specifications (Continued)
Parameter
Consistency Group (CTG)
Management of LUs while
using TCE
Pair creation using unified
LUs
Restriction during RAID
group expansion
Unified LU for data pool
Differential data
Host access to a data pool
Expansion of data pool
capacity
Reduction of data pool
capacity
Failures
Data pool usage at 100%
Array restart at TCE
installation
TCE use with TrueCopy
TCE use with SnapShot
TCE use with
ShadowImage
TCE use with LUN
Expansion
Hitachi AMS 2000 Family TrueCopy Extended Distance User Guide
• Maximum allowed: 16
• Maximum # of pairs allowed per consistency group:
- AMS2100: 1,022
- AMS2300: 2,046
- AMS2500: 2,046
A TCE pair must be deleted before the following operations:
• Deleting the pair's RAID group, LU, or data pool
• Formatting an LU in the pair
• Growing or shrinking an LU in the pair
• A TCE pair can be created using a unified LU.
- When array firmware is less than 0852/A, the size of each LU
making up the unified LU must be 1 GB or larger.
- When the array firmware is 0852/A or later, there are no
restrictions on the LUs making up the unified LU.
• LUs that are already in a P-VOL or S-VOL cannot be unified.
• Unified LUs that are in a P-VOL or S-VOL cannot be released.
A RAID group in which a TCE P-VOL or data pool exists can be expanded
only when pair status is Simplex or Split.
If the TCE data pool is shared with SnapShot, the SnapShot pairs must
be in Simplex or Paired status.
Not allowed.
When pair status is Split, data sent to the P-VOL and S-VOL are
managed as differential data.
A data pool LU is hidden from a host.
• Data pools can be expanded by adding an LU.
• Mixing SAS/SSD and SATA drives in a data pool is not supported.
Set all configured LUs using the same drive type.
Yes. The pairs associated with a data pool must be deleted before the
data pool can be reduced.
• When the copy operation from P-VOL to S-VOL fails, TCE suspends
the pair (Failure). Because TCE copies data to the remote S-VOL
regularly, data is restored to the S-VOL from the update
immediately before the occurrence of the failure.
• A drive failure does not affect TCE pair status because of the RAID
architecture.
When data pool usage is 100%, the status of any pair using the pool
becomes Pool Full. P-VOL data cannot be updated to the S-VOL.
The array is restarted after installation to set the data pool, unless it is
also used by SnapShot. Then there is no restart.
Not Allowed.
SnapShot can be cascaded with TCE or used separately.
Only a SnapShot P-VOL can be cascaded with TCE.
Although TCE can be used at the same time as a ShadowImage system,
it cannot be cascaded with ShadowImage.
When firmware version is less than 0852/A, it is not allowed to create
a TCE pair using unified LUs, which unify the LU with 1 GB or less
capacity.
Requirements and specifications
TCE Specification
5–5