462IBM TotalStorage DS6000 Series: Performance Monitoring and Tuning
Figure 14-14 Application write I/O within two Consistency Group points
Figure 14-14 summarizes roughly what happens when Persistent Cache or NVS in the
remote storage server is over committed. A read (3) and a write (4) to preserve the source
track and write it to the C volume is required before the write (5) can complete. Eventually the
track gets updated on the B1 volume to complete write (5). But usually all writes are quick
writes to cache and persistent memory and happen in the order as Figure 14-12 on page 459
outlines.
A write I/O to the FlashCopy source volume also tr ...
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