CCI
state
Storage
system
internal
state
Description
Writing control on TC
async volume
Transfer
data via
ESCON
TrueCopy
Sync
TrueCopy Async
Writing
data
Response
Deleting N/A Deleting from PAIR using
[pairsplit -S]
Normal Usual Sidefile
Suspending N/A Suspending
from PAIR
Using
[pairsplit ]
Via Bitmap Usual Sidefile
Timeout of
over threshold
PSUS PSUS PSUS Same Via Bitmap Usual None
PFUS None Timeout Over Threshold Via Bitmap Usual None
PSUE PSUE PSUE Same (link down, etc.) Via Bitmap Usual None
PDUB PDUB PDUB Same Via Bitmap Usual None
* If the host has more write I/Os in COPY state, then host write I/Os are delayed until there is enough
space in the sidefile.
Legend:
Bitmap: Host write data is managed via a cylinder BITMAP of delta data.
Normal: Host write data is not managed by BITMAP or sidefile.
Usual: Host side writing response is not delayed.
HWM (High Water Mark): Sidefile quantity is over 30% of cache storage.
TrueCopy Async/Universal Replicator error state
In the case of an ESCON or fibre-channel (FC) failure, the S-VOL FIFO queue
is missing a data block that was transferred from the P-VOL FIFO queue. The
RCU waits to store the next sequenced data block in the S-VOL FIFO queue
until the TrueCopy Async copy pending timeout occurs (defined using
TrueCopy). In addition, the timeout value can be specified at Device Manager
- Storage Navigator. The default value is set to 5 minutes. If the timeout
occurs during this waiting state, the pair status changes from PAIR to PSUE,
and non-sequenced data blocks are managed by the S-VOL bitmap. The
missing data block can be recovered using the pairresync command, which
merges the S-VOL bitmap with the P-VOL bitmap.
Figure 6-11 TrueCopy
Async suspension condition on page 6-30 shows this situation on the
secondary side.
Data replication operations with CCI
6-29
Command Control Interface User and Reference Guide
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