CLI Guide

● 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.
[read-ahead-size disabled|adaptive|stripe|512KB|1MB|2MB|4MB|8MB|16MB|
32MB]
Optional. Controls the use and size of read-ahead cache. You can optimize a volume for sequential
reads or streaming data by changing the amount of data read in advance. Read ahead is triggered by
sequential accesses to consecutive logical block address (LBA) ranges. Read ahead can be forward
(increasing LBAs) or reverse (decreasing LBAs).
Increasing the read-ahead size can greatly improve performance for multiple sequential read streams.
However, increasing read-ahead size will likely decrease random read performance.
● disabled: Disables read ahead.
● adaptive: Enables adaptive read-ahead, which allows the controller to dynamically calculate the
optimum read-ahead size for the current workload. This is the default.
● stripe: Sets the read-ahead size 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.
● 512KB, 1MB, 2MB, 4MB, 8MB, 16MB, or 32MB: Sets a specific read-ahead size.
[write-policy write-back|write-through|wb|wt]
Optional. Sets the cache write policy, which determines when cached data is written to the disks.
The ability to hold data in cache while it is being written to disk can increase storage device speed
during sequential reads.
● write-back or wb: 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.
This is the default
● write-through or wt: 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
You can configure the write policy to automatically change from write-back to write-through when
certain environmental events occur, such as a fan failure. For details, see help for the set advanced-
settings command.
volume
The name or serial number of the volume to change. A name that includes a space must be enclosed
in double quotes.
volume |all
Specifies either:
● The name or serial number of the volume to change. A name that includes a space must be
enclosed in double quotes.
● all: Apply the changes to all volumes.
Examples
Set the cache policy, optimization mode, and read-ahead size for volume V1.
# set volume-cache-parameters write-policy wb optimization standard
read-ahead-size stripe V1
See also
show cache-parameters
show volumes
set volume-group
Description
Sets the name of a volume group.
NOTE: You cannot rename a volume group that is in a replication set.
164 Alphabetical list of commands