CLI Guide

Table 8. cache-parameter properties
Name Type Description
serial-number string If a volume is specified, its serial number.
volume-name string If a volume is specified, its name.
write-policy string If a volume is specified, its cache write policy.
● write-back: Write-back caching does not wait for data to be completely
written to disk before signaling the host that the write is complete. This is
the preferred setting for a fault-tolerant environment because it improves the
performance of write operations and throughput.
● write-through: Write-through caching significantly impacts performance
by waiting for data to be completely written to disk before signaling the
host that the write is complete. Use this setting only when operating in an
environment with low or no fault tolerance.
write-policy-numeric uint32 Numeric equivalents for write-policy values.
● 0: write-through
● 1: write-back
cache-optimization string If a volume is specified, its cache optimization mode.
● standard: This controller cache mode of operation is optimized for
sequential and random I/O and is the optimization of choice for most
workloads. In this mode, the cache is kept coherent with the partner
controller. This mode gives you high performance and high redundancy.
● no-mirror: In this mode of operation, the controller cache performs the
same as the standard mode with the exception that the cache metadata is not
mirrored to the partner. While this improves the response time of write I/O, it
comes at the cost of redundancy. If this option is used, the user can expect
higher write performance but is exposed to data loss if a controller fails.
cache-optimization-numeric uint32 Numeric equivalents for cache-optimization values.
● 0: standard
● 2: no-mirror
read-ahead-size string The read-ahead cache setting of the volume.
● Disabled: Read-ahead is disabled.
● Adaptive: Adaptive read-ahead is enabled, which allows the controller to
dynamically calculate the optimum read-ahead size for the current workload.
● Stripe: Read-ahead is set to one stripe. The controllers treat NRAID and
RAID-1 disk groups internally as if they have a stripe size of 512 KB, even
though they are not striped.
● 512 KB, 1 MB, 2 MB, 4 MB, 8 MB, 16 MB, or 32 MB: Size selected by a
user.
read-ahead-numeric uint32 Numeric equivalents for read-ahead-size values.
● -2: Stripe
● -1: Adaptive
● 0: Disabled
● 524288: 512 KB
● 1048576: 1 MB
● 2097152: 2 MB
● 4194304: 4 MB
● 8388608: 8 MB
● 16777216: 16 MB
● 33554432: 32 MB
292 API basetype properties