Dynamic Runtime Attributes

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Field issues can occur where customers must know which initiator on a host is holding a reservation in a drive or preventing the media from being unloaded. Also, they must correlate which special file name is used for the drive (such as rmt2). Sometimes this issue occurs over transport bridges and translators, thus losing any transport identifiers to help this effort. LTO5, 3592 E07, 3592 E08, and later physical tape drives support attributes set to the drive dynamically by a host. This function is called Dynamic Runtime Attributes (DRA). Atape supports the feature, starting from 12.5.9.0.

The feature is enabled by default. The drive attributes on the host are set during the open, close, device reset, and data path change only. So, it does not have impact on the tape and system performance. The error is ignored and is not returned to application, when the information failed to send. However, a device attribute named as "host_attributes" is available to disable the DRA feature, when Atape runs with the virtual tape library for which the feature is not supported.

Run the lsattr command to display the attribute of host_attributes setup.

On LTO tape drive:

# lsattr -El rmt1
host_attributes yes    Host Dynamic Runtime Attribute (LTO-5 and later only) True

On 3592 tape drive:

# lsattr -El rmt4
host_attributes yes    Host Dynamic Runtime Attribute for 3592-E07 and later True

To modify the attribute of "host_attribute", run the chdev command.

# chdev -lrmt1 -a host_attributes=no
rmt1 changed