Hitachi TAGMASTORE MK-90RD011-25, User Manual

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Hitachi Command Control Interface (CCI) User and Reference Guide 27
Table 2.6 State Table for Hitachi TrueCopy Sync vs. TrueCopy Async
Description Writing Control on TC Async Vol CCI
State Storage
System
Internal State
TC Sync TC Async Writing data Response
Transfer
data via
ESCON
SMPL SMPL SMPL Same Normal Usual None
COPY COPY COPY Same Via Sidefile Usual [Note 1] Sidefile &
bitmap
Deleting N/A SMPL from COPY by using [pairsplit -S] Normal Usual Sidefile
Suspending N/A PSUS from COPY by using [pairsplit] Via Bitmap Usual Sidefile
PAIR PAIR Synchronized Less than HWM Via Sidefile Usual Sidefile
PFUL N/A
Asynchronized
sidefile in use
HWM to Threshold Via Sidefile Delayed Sidefile
Over Threshold Via Sidefile Wait until under
threshold
Sidefile
Deleting N/A SMPL from PAIR by using [pairsplit -S] Normal Usual Sidefile
Suspending N/A Using [pairsplit ] Via Bitmap Usual Sidefile PSUS from
PAIR
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
Note 1: If the host has more Write I/Os in COPY state, then host Write I/Os will be delayed
until there is enough space in the sidefile.
Explanation of terms in Table 2.6:
„
Bitmap: Host writes noted (without ordering) in a delta data bit map.
„
Normal: Host side writing 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 total cache storage (minus
Cache Residency Manager usage).
(1) Suspending, [Deleting] status. These are temporary states internal to the storage system,
and CCI cannot detect these states definitely because they are reported on the previous
state from the storage system. Therefore these states are concealed inside of pairsplit
command. After a pairsplit command has been accepted, host side write I/O for primary
volume will be managed by the BITMAP[NORMAL]: non-transmitted data which remains in the
FIFO queue of the primary volume is transferred to FIFO queue of the secondary volume, and
pair status will be set to “PSUS” [“SMPL”] state when data transfer is complete.
(2) PFUL status. If sidefile quantity is over 30% of cache storage, then internal status of the
storage system is “PFUL”, and host side write I/O is being with delayed response of range
from 0.5 seconds (minimum) to 4 seconds (maximum).