Writes Pending Test

This test reports the percentage of data that is yet to be written to the cache, and thus sheds light on a potential cache overload or a slowdown while writing data from the cache to the disk.

arget of the test : A Hitachi USP storage device

Agent deploying the test : A remote agent

Outputs of the test : One set of results for every cache logical partition on the Hitachi USP device monitored.

Configurable parameters for the test
Parameter Description

Test Period

How often should the test be executed.

Host

The IP address of the host for which this test is to be configured.

Port

The port at which the specified host is listening. By default, this is set to NULL.

UserID, Password and Confirm password

The test should be configured with the credentials of a special user account, which is specifically created for use with the export utility; this account should fulfill the following conditions:

  • Should not possess the ‘write’ permission;
  • Can be of any user type; however, to ensure that the eG agent collects statistics pertaining to all storage partitions, it is recommended that this user is of type storage administrator;

Provide the credentials of this user against the UserID and Password parameters. Confirm the password by retyping it in the Confirm Password text box.

Timeout

Specify the duration (in seconds) within which the SNMP query executed by this test should time out in this text box. The default is 3 seconds.
Measurements made by the test
Measurement Description Measurement Unit Interpretation

Writes pending rate

Indicates the ratio of write-pending data to cache memory capacity.

Percent

A high value of this measure or a value close to 100% is a cause for concern, as it indicates that too much data is yet to be written to the cache. This essentially means that the cache does not have enough space to accommodate the pending data. Such an event could occur if the cache is unable to write data to the disk quickly; a slowdown in writes to disk can severely hamper the cache’s ability to make space for data waiting to be written, thus rendering the write data pending for a long time.