8100 Updating Product Software Guide (XCS 6.250) (5697-1716, February 2012)

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Table 3 HP P6000 Performance Data Collector virtual disk statistics (continued)

DescriptionCounter

The rate at which data is written to the virtual disk by all hosts; includes transfers from

the source array to the destination array.

Write MB/s

The average time it takes to complete a write request (from initiation to receipt of write

completion).

Write Latency (ms)

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

Flush MB/s

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

Mirror MB/s

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 always 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 data stream is detected. A sequential data stream

Prefetch MB/s

may be created by host I/O and other I/O activity that occurs because of a DR initial

copy or DR full copy.

Managing host I/O timeouts for an online upgrade

The defaults for host operating parameters, such as LUN timeout and queue depth, ensure proper

operation with the storage system. These values are appropriate for most storage system operations,

including online controller software upgrades. In general, host LUN timeouts of 60 seconds or

more are sufficient for an online upgrade. In most situations you will not need to change these

settings to perform an online controller software upgrade.

If any host timeout values have been changed to less than the default (60 seconds), you must reset

them to their original default. The following sections summarize the steps and commands for

checking and changing timeout values for each supported operating system. See the operating

system documentation for more information.

NOTE:

• Depending on your operating system, changing timeout values may require a reboot of your

system.

• To minimize disruption of normal operations, schedule reboots one node at a time.

HP-UX

CAUTION: Because HP-UX supports boot across Fibre Channel SAN, any change to default SCSI

timeouts on the HP-UX host may cause corruption and make the system unrecoverable.

Default timeout values

• Sdisk timeout: 30 seconds

• (LVM) lvol timeout: 0 seconds

26 Pre-upgrade tasks