Managing Host I/O Timeouts For An Online Upgrade - HP 6400/8400 Software Manual

Counter
Read Miss Data Rate
Read Miss Latency
Write Req/s
Write Data Rate
Write Latency
Flush Data Rate
Mirror Data Rate
Prefetch Data Rate

Managing host I/O timeouts for an online upgrade

The default values for host operating parameters such as LUN timeout and queue depth are typically
set to values that ensure proper operation with the storage system. These values are appropriate for
most storage system operations, including online firmware upgrades. In general, host LUN timeouts
of 60 seconds or more are adequate to accommodate an online upgrade. In most situations it will
not be necessary to alter these settings to perform an online firmware upgrade.
If any host timeout values have been decreased to less than 60 seconds, it will be necessary to reset
them to their original default value. The following section provide a summary of the steps and commands
involved in checking and changing timeout values for each supported operating system. See the
operating system documentation for more information.
HP StorageWorks Enterprise Virtual Array updating product software guide (XCS 09522000)
Description
The rate at which data is read from physical disks because the data was not
present in the array cache memory.
The average time it takes to complete a read request (from initiation to informa-
tion receipt) from the physical disks.
The number of write requests per second completed to a virtual disk that were
received from all hosts. Write requests may include transfers from a source array
to this array for data replication and host data written to snapshot or snapclone
volumes.
The rate at which data is written to the virtual disk by all hosts and includes
transfers from the source array to the destination array.
This average time it takes to complete a write request (from initiation to receipt
of write completion).
The rate at which data is written to a physical disk for the associated virtual
disk. The sum of flush counters for all virtual disks on both controllers is the rate
at which data is written to the physical drives and is equal to the total host write
data. Data written to the destination array is included. Host writes to snapshots
and snapclones are included in the flush statistics, but data flow for internal
snapshot and snapclone normalization and copy-before-write activity are not
included.
The rate at which data travels across the mirror port to complete read and write
requests to a virtual disk. This data is not related to the physical disk mirroring
for Vraid1 redundancy. Write data is always copied through the mirror port
when cache mirroring is enabled for redundancy. In active/active controllers,
this counter includes read data from the owning controller that must be returned
to the requesting host through the proxy controller. Reported mirror traffic is al-
ways outbound from the referenced controller to the other controller.
The rate at which data is read from the physical disk to cache in anticipation
of subsequent reads when a sequential stream is detected. Note that a sequential
data stream may be created by host I/O and other I/O activity that occurs be-
cause of a DR initial copy or DR full copy.
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