Components of the Alternate Store Location Feature

fs_altstore Resident Process

The fs_altstore resident process is running whenever TSM is running. It is visible in process listings. There are no command-line parameters, and the process must not be run by hand. Its configurable options are controlled by the following editable settings as described in the
/usr/adic/TSM/config/fs_sysparm.README file.

Sysparm Parameters

ALTSTORE_AGENT_PORT_NUMBER

Communication between the altstore processes running on the main and remote sites is through a TCP socket on the designated port number 12333. This port number must be allowed to be passed through any firewalls between the two sites. This value must be identical on both main and remote sites.

Default: 12333

ALTSTORE_MAX_CONNECTIONS

This specifies the maximum number of connections between a remote-site Altstore daemon and all of the main-site Altstore daemons it serves. For Altstore daemons acting as a remote-site, this value should be equal to or greater than the sum of the values (ALTSTORE_NUM_TXFR_STREAM + 1) for each main-site. For Altstore daemons acting as a main-site only, the default value is recommended.

Default: (ALTSTORE_NUM_TXFR_STREAM + 1) or 31, whichever is larger.

ALTSTORE_NUM_BG_TXFR_STREAM

This specifies the number of simultaneous transfer streams for background transfers in the Alternate Store Location feature. This is the maximum number of transfer streams that can be used for transferring background files when the streams are not being used for on-demand transfers. This limit ensures that on-demand transfers can be responsive when new transfers are needed. This number must be less than or equal to ALTSTORE_NUM_TXFR_STREAM.

Default: 2. The valid range is 1 through 30.

ALTSTORE_NUM_SCRATCHPOOL

This is the number of internal working-queue elements. It should be about 40 times the number of simultaneous transfer streams specified by ALTSTORE_NUM_TXFR_STREAM.

Default: 200. The valid range is 10 through 3000.

ALTSTORE_NUM_TXFR_STREAM

This specifies the number of simultaneous transfer streams for on-demand transfers in the Alternate Store Location feature. The optimal number depends on the number of CPU cores in the server computer, the capacity of the network hardware, the ability of the destination computer to handle traffic, and the contention with other services using the network. Experimentation can help to characterize system throughput and determine when this number reaches diminishing returns of total throughput.

Default: 5. The valid range is 1 through 30.

ALTSTORE_POLL_TIME

Time to wait (in seconds) before the altstore daemon wakes up to check for alternate store location candidates. The default value is 60 seconds. The valid range is 60 to 300 seconds. A longer value reduces the system resources consumed. A shorter value reduces the delay for the system to recognize the start or end of a lockout period as described in section: fsschedlock.

Default: 60

ALTSTORE_RTRV_WAIT_COUNT

When retrieving truncated files, the Alternate Store Location feature will wait for this number of retrievable files to accumulate if the ALTSTORE_RTRV_WAIT_TIME limit does not expire first.

Default: 10. The valid range is 1 through 30.

ALTSTORE_RTRV_WAIT_TIME

When retrieving truncated files, the Alternate Store Location feature will wait up to this many seconds for a batch of retrievable files to accumulate if the ALTSTORE_RTRV_WAIT_COUNT is not reached first.

Default: 30. The valid range is 1 through 900.

ALTSTORE_TXFR_SCRIPT

Pathname of the customizable script for transferring files with the Alternate Store Location feature.

Default: /usr/adic/TSM/bin/fs_altstore_transfer

ALTSTORE_TXFR_USERNAME

The altstore user ID owns the staging directory on the remote site and is used as the target ID for file transfers. The value must be identical on both main and remote sites.

Default: altstore

ALTSTORE_VERSIONING

This value is configured on the source MDC and controls the behavior that occurs on the Alternate Store Location target MDC for existing files when they are being updated. The 'y' option causes the file to be overwritten, which creates another Storage Manager version of the file on the target MDC. This option incurs higher CPU overhead. The 'n' option causes the file to be re-created, which creates the first Storage Manager version of a new file on the target MDC. This option incurs lower CPU overhead.

Default: y

WARNING: Use of the fsversion command to retrieve a different version of a file on either the main or remote site can result in a discrepancy between the sites. Use the fsversion feature with caution. When it is necessary to restore a main-site file to an older version, the main- and remote-site files can be kept in sync by rewriting a portion of the file on the main site, which will cause it to be stored as a new version on both the main and remote sites.

ALTSTORE_VERSIONING_TIMEOUT_FACTOR

This value is configured on the main-site MDC and controls the amount of time that is allowed for file overwrites to occur on the remote-site MDC before being considered an error. This value is only applicable when ALTSTORE_VERSIONING is set to 'y'. The versioning timeout factor is specified in seconds per gigabyte of data. This value should be increased if file overwrites are timing out.

Default: 60. The valid range is 30 through 600.