Example Procedure For Moving Data; Process For Disaster Recovery; Takeover Processing - Hitachi AMS 2000 User Manual

Example procedure for moving data

1. Stop the applications that are writing to the P-VOL, then un-mount the
P-VOL.
2. Split the TCE pair. Updated differential data on the P-VOL is transferred
to the S-VOL. Data in the S-VOL is stabilized and usable after the split is
completed.
3. Mount the P-VOL and then resume writing to the P-VOL.
4. Mount the S-VOL.
5. Read and analyze the S-VOL data. The S-VOL data can be updated, but
updated data will be lost when the TCE pair is resynchronized. If updated
data is necessary, be sure to backup the S-VOL on the remote side.
6. Un-mount the S-VOL.
7. Re-synchronize the TCE pair.

Process for disaster recovery

This section explains behaviors and the general process for continuing
operations on the S-VOL and then failing back to the P-VOL, when the
primary site has been disabled.
In the event of a disaster at the primary site, the cycle update process is
suspended and updating of the S-VOL stops. If the host requests an S-VOL
takeover (CCI horctakeover), the remote array restores the S-VOL using
data in the data pool from the previous cycle.
The AMS version of TCE does not support mirroring consistency of S-VOL
data, even if the local array and remote path are functional. P-VOL and S-
VOL data are therefore not identical when takeover is executed. Any P-VOL
data updates made during the time the takeover command was issued
cannot be salvaged.

Takeover processing

S-VOL takeover is performed when the horctakeover operation is issued by
the secondary array. The TCE pair is split and system operation can be
continued with the S-VOL only. In order to settle the S-VOL data being
copied cyclically, it is restored using the data that was pre-determined in the
preceding cycle and saved to the data pool, as mentioned above. The S-VOL
is immediately enabled to receive the I/O instruction.
When the SVOL_Takeover is executed, data restoration processing from the
data pool of the secondary site to the S-VOL is performed in the
background. During the period from the execution of the SVOL_Takeover
until the completion of the data restoration processing, performance of the
host I/O for the S-VOL is deteriorated. P-VOL and S-VOL data are not the
same after this operation is performed.
Hitachi AMS 2000 Family TrueCopy Extended Distance User Guide
Example scenarios and procedures
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