About the stager.cmd File

About the `stager.cmd` File

In the stager.cmd file, specify directives to override the default behaviors. You can configure the stager to stage files immediately, to never stage files, to staging partially, and to specify other staging actions. For example, specifying the never-stage attribute benefits applications that access small records from large files because the data is accessed directly from the archive media without staging the file online.

This section describes the stager directives. For additional information about stager directives, see stager.cmd(4) in Sun QFS and Sun Storage Archive Manager Reference Manual. If you are using the SAM-QFS Manager software, you can control staging from the File System Summary or File System Details page. You can browse the file system and see the status of individual files, use filters to view certain files, and select specific files to stage. You can select which copy to stage from or let the system choose the copy.

Example 15-1 stager.cmd File

The following example shows a stager.cmd file after all possible directives have been set.

# This is stager.cmd file /etc/opt/SUNWsamfs/stager.cmd
drives=dog 1
bufsize=od 8 lock
logfile=/var/adm/stage.log
maxactive=500

How to Create a `stager.cmd` File

In the /etc/opt/SUNWsamfs/stager.cmd file, add the directives to control staging at your site, according to the information in the following sections:
Save and close the stager.cmd file.
Propagate the file changes and restart the system.
```
# samd config
```

`drives` Directive: Specifying the Number of Drives for Staging

By default, the stager uses all available drives when staging files. If the stager keeps all the drives busy, it can interfere with the archiver's activities. The drives directive specifies the number of drives available to the stager. This directive has the following format:

drives = library count

Argument	Definition
library	The family set name of a library as it appears in the `mcf` file.
count	The maximum number of drives to be used. By default, this is the number of drives configured in the `mcf` file for this library.

Example 15-2 Drives Directive

The following example specifies that only one drive from the dog family set's library is used for staging files:

drives = dog 1

`bufsize` Directive: Setting the Stage Buffer Size

By default, a file being staged is read into memory in a buffer before being restored from the archive media to disk cache. Use the bufsize directive to specify a buffer size and, optionally, to lock the buffer. These actions can improve performance. You can experiment with various buffer-size values. The directive has the following format:

bufsize = media buffer-size [lock]

Argument	Definition
media	Specify the archive media type from the list on the `mcf`(4) man page.
buffer-size	A number from 2 through 8192. The default is 16. This value is multiplied by the `dev_blksize` value for the media type, and the resulting buffer size is used. The `dev_blksize` value is specified in the `defaults.conf` file. The higher the number specified for `buffer-size`, the more memory is used. For more information, see defaults.conf(4) in Sun QFS and Sun Storage Archive Manager Reference Manual.
`lock`	The `lock` argument indicates that the stager should use locked buffers when staging archive copies. If `lock` is specified, the stager sets file locks on the stage buffer in memory for the duration of the copy operation. This avoids the overhead associated with locking and unlocking the buffer for each I/O request and can thereby result in a reduction in system CPU time.The `lock` argument should be specified only on large systems with large amounts of memory. Insufficient memory can cause an out-of-memory condition. The `lock` argument is effective only if direct I/O is enabled for the file being staged. By default, `lock` is not specified, and the file system sets the locks on all direct I/O buffers, including those for staging. For more information about enabling direct I/O, see setfa(1) in Sun QFS and Sun Storage Archive Manager Reference Manual , sam_setfa(3) in Sun QFS and Sun Storage Archive Manager Reference Manual , or the `-O forcedirectio` option on mount_samfs(1M) in Sun QFS and Sun Storage Archive Manager Reference Manual.

`logfile` Directive: Specifying a Log File

You can request that the SAM-QFS software collect file-staging event information and write it to a log file. By default, no log file is written. The logfile directive specifies a log file to which the stager can write logging information. The stager writes one or more lines to the log file for each file staged. This line includes information such as the name of the file, the date and time of the stage, and the volume serial number (VSN). The directive has the following format:

logfile=filename [event]

Argument

Definition

filename

Specify a full path name.

event

Specify one or more staging events. If you specify more than one event, use spaces to separate each them. Possible event specifications are as follows.

all - Logs all staging events.

start - Logs when staging begins for a file.

finish - Logs when staging ends for a file. Enabled by default.

cancel - Logs when the operator cancels a stage. Enabled by default.

error - Logs staging errors. Enabled by default.

Example 15-3 Specifying a Stager Log File

The following directive creates the /var/adm/stage.log file:

logfile=/var/adm/stage.log

Example 15-4 Stager Log File

S 2003/12/16 14:06:27 dk disk01 e.76d 2557.1759 1743132 /sam1/testdir0/filebu 1 root other root 0 -
F 2003/12/16 14:06:27 dk disk01 e.76d 2557.1759 1743132 /sam1/testdir0/filebu 1 root other root 0 -
S 2003/12/16 14:06:27 dk disk02 4.a68 1218.1387 519464 /sam1/testdir1/fileaq 1 root other root 0 -
S 2003/12/16 14:06:43 dk disk01 13.ba5 3179.41 750880 /sam1/testdir0/filecl 1 root other root 0 -
F 2003/12/16 14:06:43 dk disk01 13.ba5 3179.41 750880 /sam1/testdir0/filecl 1 root other root 0 -
S 2003/12/16 14:06:59 dk disk01 17.167b 1155.1677 1354160 /sam1/testdir0/filedb 1 root other root 0  /
-
F 2003/12/16 14:06:59 dk disk01 17.167b 1155.1677 1354160 /sam1/testdir0/filedb 1 root other root 0  /
-
S 2003/12/16 14:06:59 dk disk02 f.f82 3501.115 1458848 /sam1/testdir1/filecb 1 root other root 0 -
S 2003/12/16 14:07:15 dk disk01 1f.473 1368.1419 636473 /sam1/testdir0/fileed 1 root other root 0 -
S 2003/12/16 14:07:15 dk disk02 16.f15 3362.45 1065457 /sam1/testdir1/filecz 1 root other root 0 -
S 2003/12/16 14:07:31 dk disk01 23.201d 3005.1381 556807 /sam1/testdir0/fileeq 1 root other root 0 -
S 2003/12/16 14:07:47 dk disk01 26.c4d 2831.1113 1428718 /sam1/testdir0/fileez 1 root other root 0 -
S 2003/12/16 14:07:47 dk disk02 1b.835 3736.59 1787855 /sam1/testdir1/filedp 1 root other root 0 -

The following table describes the content of the stager log file fields.

Field	Example Value	Content Description
1	S	Stage activity - `S` for start, `C` for canceled, `E` for error, `F` for finished.
2	2003/12/16	Date of the stage action, in yyyymm`/`dd format.
3	14:06:27	Time of the stage action, in hhmm`:`ss format.
4	dk	Archive media type. For information about media types, see mcf(4) in Sun QFS and Sun Storage Archive Manager Reference Manual.
5	disk01	VSN.
6	e.76d	Using hexadecimal format, the physical position of the start of the archive file on media (`tar`file) and the file offset on the archive file.
7	2557.1759	Inode number and generation number. The generation number is used in addition to the inode number for uniqueness because inode numbers are reused.
8	1743132	Length of the file.
9	`/sam1/testdir0/filebu`	Name of the file.
10	1	Archive copy number.
11	root	User ID of the file.
12	other	Group ID of the file.
13	root	Group ID of the requestor.
14	0	Equipment ordinal of the drive from which the file was staged.
15	`-`	A `V` in this field indicates that data verification is being used for the file.

`maxactive` Directive: Specifying the Number of Stage Requests

The maxactive directive enables you to specify the number of stage requests that can be active at any one time. The directive has the following format:

maxactive=number

By default, number is 4000. The minimum number allowed is 1. The maximum allowed is 500,000.

The following example specifies that no more than 500 stage requests can be in the queue simultaneously:

maxactive=500

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	Sun Storage Archive Manager 5.3 Configuration and Administration Guide Sun QFS and Sun Storage Archive Manager 5.3 Information Library

How to Create a stager.cmd File

drives Directive: Specifying the Number of Drives for Staging

bufsize Directive: Setting the Stage Buffer Size

logfile Directive: Specifying a Log File

maxactive Directive: Specifying the Number of Stage Requests