zfsadm decompress

Purpose

zfsadm decompress decompresses a zFS aggregate that was previously compressed with the zEDC compression method.

Options

-aggregate name

Specifies the name of the aggregate to be decompressed. The aggregate name is not case-sensitive. It is always converted to uppercase.

-cancel

Cancels an in-progress decompress operation for the specified aggregate.

-help

Prints the online help for this command. All other valid options that are specified with this option are ignored.

-level

Prints the level of the command. This option is useful when you are diagnosing a problem. Except for -help, all other valid options that are specified with -level are ignored.

-trace file_name

Specifies the name of the file that will have the trace records written into it. The trace file can be a z/OS UNIX file, an existing MVS sequential data set, or a member of either an existing partitioned data set (PDS) or partitioned data set extended (PDSE). Use this option only at the direction of IBM Support.

For information about preallocation instructions for debugging, see Step 5 (Optional) Preallocate data sets for debugging in zFS installation and configuration steps.

Because MVS data set names must be fully qualified, z/OS UNIX has special rules for specifying MVS data set names in the shell environment. For more information, see Specifying MVS data set names in the shell environment in z/OS UNIX System Services Command Reference.

Usage notes

1. The zfsadm decompress command is a long-running administrative command that uses the zEDC decompression method to decompress an existing compressed zFS aggregate.
2. To process the decompression request, the long-running command thread pool must have an available foreground thread. See the IOEFSPRM configuration option long_cmd_threads for information about controlling the size of the long-running foreground and background thread pools. ( IOEFSPRM)
3. The command must be issued from a z/OS V2R3 or later system, and the zFS file system must be zFS-owned on a z/OS V2R3 or later system. The aggregate must be at least aggregate version 1.5 and mounted read/write. If you ever need to go back to an earlier z/OS V2R3 system, make sure to decompress all previously compressed aggregates first.
4. Applications can still access the aggregate while it is being decompressed.
5. A decompress operation can be interrupted by using the -cancel option or during a shutdown. It can also be interrupted when the shell command unmount or TSO/E command UNMOUNT is issued with the force option. If the decompress operation is interrupted, the zFS aggregate might end up with both compressed and decompressed files. This partial state is allowed. You can issue another zfsadm decompress command to resume the decompress operation for the rest of files after the interruption. You can also issue zfsadm compress command to compress the partially compressed aggregate.
6. You cannot decompress an aggregate that is in a partially encrypted or partially decrypted state. In other words, if encryption or decryption was interrupted for an aggregate, you cannot decompress it.
7. Use either the zfsadm fsinfo or MODIFY FSINFO command to display whether an aggregate is decompressed or being decompressed. Progress of the decompress operation can be seen in the owner status display. The backup change activity flag is set if any data is decompressed.
8. The zfsadm fileinfo command can be used to show whether a particular file is decompressed.
9. Aggregates with active file backups cannot be decompressed.

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