C H A P T E R 6

Recycling

Recycling is the process of reclaiming space on archive volumes. The recycler works with the archiver to reclaim the space occupied by unused archive copies. As users modify files, the archive copies associated with the old versions can be purged from the system. The recycler identifies the volumes with the largest proportions of expired archive copies and directs the movement of unexpired copies to different volumes. If only expired copies exist on a given volume, a site-defined action is taken. For example, such a volume can be relabeled for immediate reuse or exported to offsite storage, thus keeping a separate historical record of file changes. Users are unaware of the recycling process as it relates to their data files.

This chapter describes the recycling process and directives. It includes the following topics:

- Recycling Process Overview

- Using Recycling Directives

- Planning Recycling Operations

##

Recycling Process Overview

The recycler keeps the amount of space consumed by expired archive copies to a minimum as defined by site-specified parameters. At any time, the space on a given archive volume consists of the following:

- Current data, consisting of archive images that are active currently.

- Expired data, consisting of archive images that are no longer active currently.

- Free space, consisting of space that is not being used by currently active or expired archive images.

The capacity of a volume is the total amount of space for data on a volume. For example, a 10-gigabyte tape volume with 3 gigabytes written to it has a capacity of 10 gigabytes and 7 gigabytes of free space.

New or newly labeled archive media starts out with all its capacity as free space. As data is archived to the media, the amount of free space decreases and the amount of current data increases.

As archived files in the file system are changed or removed, their archive images expire and they move from the current data classification to the expired data classification. The physical space used by these images remains the same; there is simply no longer a file in the file system pointing to that space. Only when space is recycled can these images be removed and the space they occupy become free. The goal of the recycler is to transform space used by expired data into free space without losing any current data.

You initiate recycling by entering the `sam-recycler`(1M) command either manually or through a `cron`(1) job. TABLE 6-1 shows recycling methods.

TABLE 6-1 Recycling Methods and Media Types
Recycling Method | Media and Notes
--- | ---
By automated library | Removable media cartridges. When you archive by library, you put recycling directives in the `recycler.cmd` file.
By archive set | Removable media cartridges and disk. When you archive by archive set, you put all recycling directives in the `archiver.cmd` file.

As TABLE 6-1 shows, you can recycle either by library or by archive set. If you are archiving to disk, you can recycle only by archive set.

The recycler and the archiver work together, as follows:

1. The recycler marks all the current (valid) archive images that are present on a volume with the `rearchive` attribute.

2. If you are archiving to removable media, the recycler marks the selected archive volume with the `recycle` attribute. This prevents the archiver from writing any more archive images to the volume.

3. The archiver moves all the marked images to another volume. This operation is called rearchiving. After the archiver moves the current archive images from the old volume to the new volume, the old volume contains only free space and expired space. If you are archiving to removable media cartridges, you can relabel and reuse the cartridge. If you are archiving to disk, the recycler removes the file that contains the expired archive images.

The recycler is designed to run periodically. It performs as much work as it can each time it is invoked. The recycler has to finish marking copies for rearchiving before the archiver can rearchive the files.

Sometimes expired archive images, with the `rearchive` attribute set, remain on media. This can happen under the following conditions:

- The archiver does not run after the recycler marks expired archive images.

- Media is not available for the archiver to use when moving the unexpired archive images.

- There are miscellaneous archiver anomalies.

Between executions, the recycler keeps state information in the library catalogs and the inodes. During the recycling process, you can use the `sls`(1) command and its `-D` option to display information about a file. The output from the `sls`(1) command shows whether or not a file is scheduled for rearchiving.

##

Using Recycling Directives

The `recycler.cmd` file accepts the directives described in the following sections:

- Specifying a Log File: The logfile Directive

- Preventing Recycling: The no_recycle Directive

- Specifying Recycling for an Entire Automated Library: The Library Directive

### Specifying a Log File: The `logfile` Directive

The `logfile` directive specifies a recycler log file. This directive has the following format:

    logfile = filename

For filename, specify the path to the log file.

The following is an example of a `logfile=` directive line:

    logfile=/var/adm/recycler.log

### Preventing Recycling: The `no_recycle` Directive

The `no_recycle` directive enables you to prevent recycling of volumes. To specify the VSNs, you use regular expressions and one or more specific media types.

This directive has the following format:

    no_recycle media-type VSN-regexP [ VSN-regexP ... ]

TABLE 6-2 Arguments for the `no_recycle` Directive
Argument | Meaning
--- | ---
media-type | A media type from the `mcf`(4) man page.
VSN-regexp | One or more space-separated regular expressions to describe the volumes. For information, see the `regexp`(5) man page or see File Name search-criterion Using Pattern Matching: -name regex.

By specifying a media type, you can prevent the recycling of volumes stored on a particular type of media. One or more VSN-regexp specifications enable you to identify specific cartridges to be excluded from recycling.

For example, the following directive line excludes from recycling any tape volumes whose VSN identifiers begin with `DLT`:

    no_recycle lt DLT.*

### Specifying Recycling for an Entire Automated Library: The Library Directive

The library directive enables you to specify various recycling parameters for the VSNs associated with a specific library.

This directive has the following format:

    library parameter [ parameter ... ]

For library, specify the library's name as specified in the family set field of the `mcf`(4) file.

For parameter, specify one or more space-separated parameter keywords from TABLE 6-3.

TABLE 6-3 Library Directive parameter Values
parameter Value | Meaning
--- | ---
`-dataquantity` size | Maximum amount of data that the recycler can schedule for rearchiving in its efforts to clear volumes of useful data. Default is 1 gigabyte.
`-hwm` percent | Library high water mark. Default is 95.
`-ignore` | Directive that prevents volumes in this library from being recycled. This directive is useful during testing of the `recycler.cmd` file.
`-mail` email-address | E-mail addresses to which recycling email messages are to be sent. By default, no email is sent.
`-mingain` value | Minimum VSN gain. Default is 50.
`-vsncount` count | Maximum number of recycled volumes to be counted. Default is 1.

For example, consider the following directive line:

    gr47 -hwm 85 -ignore -mail root -mingain 40

It specifies the following for library `gr47`:

- The library should be considered for recycling when the volumes in the library are 85 percent full.

- The minimum percent gain is 40 percent.

- Only one volume is to be recycled. This is also a default setting.

- Recycling messages are emailed to `root`.

In addition, no more than 1 gigabyte is to be rearchived. This is the default, so it is not specified in the `recycler.cmd` file.

##

Planning Recycling Operations

Before configuring the recycler, note the following:

- Directives in the `archiver.cmd` file control recycling by archive set. Directives in the `recycler.cmd` file control recycling by library. In addition, the `recycler.cmd` file controls general recycler behavior. For information on recycler directives, see Using Recycling Directives.

- Do not recycle volumes that contain removable media files. You create removable media files by using the `request`(1) command. A volume with removable media files can never be drained.

- Do not run the recycler while performing maintenance on a Sun StorEdge SAM-FS file system. The recycler uses the `.inodes` file and the `mcf` file to help identify files that are current or expired and the devices associated with a file system. Absence of proper information in these files can cause current archived data to appear as expired and be recycled.

- All Sun StorEdge SAM-FS file systems must be mounted when the recycler is run. If you are recycling from online disk, the file system that contains the disk volumes must be mounted and the host system must be accessible.

The recycler is not enabled by default. You must initiate recycling by entering the `sam-recycler`(1M) command. When the recycler is initiated, the default recycler settings specified in Specifying Recycling for an Entire Automated Library: The Library Directive take effect. For more information on the recycler, see the `sam-recycler`(1M) man page.

Configuring the recycler involves the tasks described in the following sections, in this order:

1. Creating a recycler.cmd File

2. Editing the archiver.cmd File

3. Running the Recycler

4. Creating a crontab File for the Recycler

5. Removing -recycle_ignore and ignore Parameters

6. Creating a recycler.sh File

If you are archiving to cartridges in a library, this process involves creating a `recycler.cmd` file and, optionally, editing the `archiver.cmd` file. If you are archiving to disk, editing the `archiver.cmd` file.

The following procedures describe configuring the recycler for any archive media using the `recycler.cmd` and `archiver.cmd` files.

### Creating a `recycler.cmd` File

Perform this step if you are recycling archive copies on cartridges in a library.

Note - Even if you are recycling by archive set, you still should configure each library in the `recycler.cmd` file. This ensures that VSNs that do not fall into an archive set can be recycled if needed.

The `recycler.cmd` file contains general recycling directives and can also contain directives for each library in the Sun StorEdge SAM-FS environment. A typical `recycler.cmd` file contains the following directive lines:

- A `logfile=` directive line to specify a recycler log file. The system writes recycling messages and recycling reports to this file.

- One or more directive lines for each library that contains volumes to be recycled. This line must contain the family set name (from the `mcf` file) for the library being recycled. This identifies the library to the recycler. For information on the recycling directive, see Using Recycling Directives.

Because you are creating the `recycler.cmd` line and it has not yet been tested, use the `ignore` keyword. You remove the `ignore` keyword in a later step in this process.

To create a `recycler.cmd` file, perform the following steps:

1. Become superuser.

2. Use `vi`(1) or another editor to open file `/etc/opt/SUNWsamfs/recycler.cmd`.

3. Add one or more directives described in this chapter to control recycler activity.

4. Save and close the file.

Alternatively, you can create a recycler.cmd file by using File System Manager software. For more information, see the File System Manager online help.

#### Example `recycler.cmd` File

CODE EXAMPLE 6-1 shows an example of a `recycler.cmd` file.

CODE EXAMPLE 6-1 Example `recycler.cmd` File
    logfile = /usr/tmp/recycler.log
    stk30  -hwm 51  -mingain 60  -ignore  -mail  root

The following sections describe the parameters specified in CODE EXAMPLE 6-1.

##### The `-hwm 51` Parameter

By specifying a high water mark, you can set the percentage of media usage below which recycling cannot occur. This percentage is the ratio of the used space in the library to its total capacity. As an example, a library that holds ten 20-gigabyte tapes, three of them 100 percent full and the remaining seven each 30 percent full, has the following media utilization percentage:

    ((3* 1.00 + 7 * 0.30) * 20G ) / ( 10 * 20G ) * 100%= 51%

Note that this calculation does not distinguish between current data and expired data. It only addresses the amount of media used.

In this example, if the utilization percentage is 51 percent or less, the recycler does not automatically select any of the automated library's VSNs for recycling.

Note - You can force a VSN to be recycled by using the following command to set the recycling flag: # `chmed +c lt.`VSN When the `+c` flag is set, the archiver does not write any more archive images to the volume. The `+c` flag can be viewed through the `samu`(1M) utility. For more information, see the `chmed`(1M) and `samu`(1M) man pages. For information on using the `samu`(1M) operator utility, see the Sun StorEdge QFS Configuration and Administration Guide.

##### The `-mingain 60` Parameter

The minimum VSN gain percentage sets a lower limit on the amount of space to be gained by recycling a cartridge. For example, if a cartridge in an automated library is 95 percent current data and 5 percent expired data, the gain obtained by recycling the cartridge would be only 5 percent. It might not be worth moving the other 95 percent to retrieve this space. Setting the minimum gain to 6 percent or more inhibits the recycler from automatically selecting this VSN.

##### The `-ignore` Parameter

The `-ignore` parameter keeps the recycler from recycling a particular library. Use it when you are configuring the recycler.

##### The `-mail` Parameter

The `-mail` parameter specifies that the recycler send mail when recycling occurs on a given library. The mail message has the following subject line:

    Robot robot-name recycle

TABLE 6-2 shows sample message bodies.

CODE EXAMPLE 6-2 Sample Recycling Messages
    I will recycle VSN vsn.
    Cannot find any candidate VSN in this media changer.
    Previously selected VSN vsn is not yet finished recycling.
    Previously selected VSN vsn is now finished recycling. It will now be post-recycled.

### Editing the `archiver.cmd` File

If you are archiving to disk, you must edit the archiver.cmd file in order to recycle.

If you are recycling by library, this step is optional.

To edit the `archiver.cmd` file, follow the steps described in To Create or Modify an archiver.cmd File and Propagate Your Changes.

Alternatively, you can edit the archiver.cmd file by using the File System Manager. For more information, see the File System Manager online help.

To enable recycling by archive set, you must add archive set recycling directives between the `params` and `endparams` directives. TABLE 6-4 shows the archive set recycling directives that you can use.

TABLE 6-4 Archive Set Recycling Directives
Directive | Function
--- | ---
`-recycle_dataquantity` size | Limits the amount of data that the recycler can schedule for rearchiving in its efforts to clear volumes of useful data.
`-recycle_hwm` percent | Sets the high water mark percentage.
`-recycle_ignore` | Prevents the archive set from being recycled.
`-recycle_mailaddr` mail-address | Sends recycler messages to the specified mail address.
`-recycle_mingain` percent | Limits recycling to VSNs that would increase their free space by at least the specified percentage.
`-recycle_vsncount` count | Limits the number of volumes to be rearchived to the specified value.
`-rearch_stage_copy` copy-number | Allows staging for rearchiving to take place from selected (faster) copies.

For more information about archiver directives, see Chapter 3 or see the `archiver.cmd`(4) man page.

### Running the Recycler

1. Issue the `sam-recycler`(1M) command.

The recycler reads the `recycler.cmd` file.

2. Examine the standard output log, Sun StorEdge SAM-FS log, and `/var/adm/messages` for any error messages from the recycler.

Correct your files if errors appear.

CODE EXAMPLE 6-3 shows a sample recycler log file for recycling removable media cartridges.

CODE EXAMPLE 6-3 Recycler Log File Example for Removable Media Cartridges
    ========== Recycler begins at Wed Dec 12 14:05:21 2001 ===========
    Initial 2 catalogs:
    0  Family: m160                 Path: /var/opt/SUNWsamfs/catalog/m160
       Vendor: ADIC                 Product: Scalar 100
       SLOT                  ty    capacity         space vsn
          0                  at        25.0G        25.0G CLN005
          1                  at        48.5G         6.1G 000003
          2                  at        48.5G        32.1G 000004
          3                  at        48.5G        35.1G 000005
          4                  at        48.5G        44.6G 000044
          5                  at        48.5G        45.1G 000002
          6                  at        48.5G        45.9G 000033
          7                  at        48.5G        48.5G 000001
       Total Capacity:  364.8G bytes, Total Space Available: 282.3G bytes
       Volume utilization 22%, high 95% VSN_min 50%
       Recycling is ignored on this robot.
    1  Family: hy                   Path: /var/opt/SUNWsamfs/catalog/historian
       Vendor: Sun SAM-FS           Product: Historian
       SLOT                  ty    capacity         space vsn
          (no VSNs in this media changer)
       Total Capacity:  0    bytes, Total Space Available: 0    bytes
       Volume utilization 0%, high 95% VSN_min 50%
       Recycling is ignored on this robot.
    8 VSNs:
                        ---Archives---   -----Percent-----   m160
     ----Status-----    Count    Bytes   Use Obsolete Free   Library:Type:VSN
    no-data VSN            0      0        0    87     13    m160:at:000003
    no-data VSN            0      0        0    33     67    m160:at:000004
    no-data VSN            0      0        0    27     73    m160:at:000005
    no-data VSN            0      0        0     8     92    m160:at:000044
    no-data VSN            0      0        0     7     93    m160:at:000002
    no-data VSN            0      0        0     5     95    m160:at:000033
    empty VSN              0      0        0     0    100    m160:at:CLN005
    empty VSN              0      0        0     0    100    m160:at:000001
    Recycler finished.
    ========== Recycler ends at Wed Dec 12 14:05:32 2001 ===========

CODE EXAMPLE 6-4 shows a sample recycler log file for recycling disk archive files.

CODE EXAMPLE 6-4 Recycler Log File Example for Disk Archive Files
    ---Archives---   -----Percent-----
     ----Status-----    Count    Bytes   Use Obsolete Free   Library:Type:VSN
    new candidate          0      0        0    41     59  <none>:dk:disk01
    677 files recycled from VSN disk01 (mars:/sam4/copy1)
    0 directories recycled from VSN disk01 (mars:/sam4/copy1)

### Creating a `crontab` File for the Recycler

If the system is performing as expected, you are ready to make a `crontab` entry for the superuser to run the recycler periodically, every two hours or more, depending on your site's conditions.

For instructions on creating a crontab entry, see the `cron`(1M) man page.

The following example entry in root's `crontab` file specifies that the `cron` daemon run the recycler every five minutes after the hour for every odd-numbered hour:

    5 1,3,5,7,9,11,13,15,17,19,21,23   * * * /opt/SUNWsamfs/sbin/sam-recycler

### Removing `-recycle_ignore` and `ignore` Parameters

As an alternative to the following procedure, you can use the File System Manager. For more information, see the File System Manager online help.

1. Use `vi`(1) or another editor to remove the `-recycle_ignore` parameters from the `archiver.cmd` file.

2. Use `vi`(1) or another editor to remove the `ignore` parameters from the `recycler.cmd` files.

You are now recycling.

### Creating a `recycler.sh` File

Create a recycler.sh file if you are recycling archive copies on removable media cartridges. If you are archiving only to disk, do not perform this step.

The recycler executes the `recycler.sh` script when all the current images from a VSN have been rearchived to another VSN. You should determine your site requirements for dispensing with recycled cartridges. Some sites choose to relabel and reuse the cartridges; others choose to remove the cartridges from the automated library to use later for accessing historical files.

The recycler calls the `/opt/SUNWsamfs/scripts/recycler.sh` script with the following arguments:

    Media type: $1  VSN: $2  Slot: $3  Eq: $4

For examples of the script, see the `recycler.sh`(1M) man page or `/opt/SUNWsamfs/examples/recycler.sh`. The latter shows how to relabel a recycled VSN and send mail to the superuser.

For more information, see the `recycler`(1M) and `recycler.sh`(1M) man pages.

Copyright © 2006, Sun Microsystems, Inc. All Rights Reserved.