Compression type

The type of compression that the client uses is determined by the combination of compression and client-side data deduplication that is used during backup or archive processing.

The compression algorithm that is used by the client is reported by the API in a new field in the qryRespArchiveData and qryRespBackupData structures:

dsChar_t        compressAlg[20];  /* compression algorithm name */

The following types of compression are reported:

LZ4

A faster and more efficient compression method that the client uses when a client-deduplicated object is sent to an LZ4-compatible container storage pool on the Tivoli® Storage Manager server. The server must be at version 7.1.5 or later, and must use container storage pools. Client-side LZ4 compression is used only when client-side data deduplication is enabled.

LZW

A traditional type of compression that the client uses in any of the following situations:

Client-deduplicated objects are sent to traditional (non-container) storage pools on the server.
The client object does not undergo client-side data deduplication.
The client object undergoes only traditional server-side data deduplication.

Blank field

The object is not compressed by the client. The object is not compressed because the compression option is set to no, or the option is not specified during backup or archive processing. Although the object is not compressed by the client, it might be compressed by the server.

The compression type is not configurable. It is determined by the backup-archive client at the time of backup or archive processing.

Example

The following example shows the Compresssion Type field in the output of the backup and archive queries from the 64-bit sample application dapismp:

Enter selection ==>1
                       Filespace:\fs1
                       Highlevel:\hl
                        Lowlevel:\ll
              Object Type(D/F/A):f
   Active(A),Inactive(I),Both(B):a
If root, query all owners? (Y/N):
               Object Owner Name:
   point in time date (MMDDYYYY):
   point in time time     (hhmm):
     Show detailed output? (Y/N):y
On Restore, Wait for mount?(Y/N):
Are the above responses correct (y/n/q)?


Item 1: \fs1\hl\ll
   Object type: File
   Object state: Active
   Insert date: 2016/2/3 10:57:41
   Expiration date: 0/0/0 0:0:0
   Owner:
   Restore order: 0-0-0-0-0
   Object id: 0-40967
   Copy group: 1
   Media class: Fixed
   Mgmt class: DEFAULT
   Object info is        :Tivoli Storage Manager API Verify Data
   Object info length is :73
   Estimated size : 0  4000
   Compression : YES
   Compression Type: LZ4
   Encryption : NO
   Encryption Strength : NONE
   Client Deduplicated : YES