LZ1 Compression in Notes/Domino 6
A good entry in the KnowledgeBase explaining about LZ1 compression that is now used in ND6... Enjoy!
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Title: What Is LZ1 Compression in Notes/Domino 6?
Document Number:
1090049
Problem
What is LZ1 compression?
Content
Notes/Domino 6 (ND6) uses LZ1 compression
for file attachments. LZ1 stands for "Lempel-Zev class 1";
it is a different method of compression from that of the Huffman
algorithm, which is the method by which Notes/Domino R5 compresses attachments.
Important information
from the Notes 6 Client help and Domino 6 Administrator help:
"Because LZ1 compression can save
you a considerable amount of disk space, it is favored over the Huffman
method. Be aware, however, that if you are working in an environment that
uses different versions of client and server software and you choose this
option, the attachments are automatically recompressed on the server using
the Huffman algorithm. This recompression of attachments can add significant
extra time to the process."
"If the LZ1 compression option is set on a Domino 6 database, a Notes 5 client will be unable to read the compression. The Lotus Domino 6 server converts LZ1 to Huffman compression for the Notes 5 client. This affects server performance. Implement LZ1 compression in an exclusively Lotus Notes/Domino 6 environment."
Please refer also to the following articles on the Lotus Developer Domain (LDD) site for information on compression in ND6. LDD Today articles:
"Lessons learned from the Notes/Domino 6 Early Deployment Program"
http://www-10.lotus.com/ldd/today.nsf/62f62847467a8f78052568a80055b380/32bacd5091f5dd3b00256c3f003cd054?OpenDocument&Highlight=0,LZ1 includes
"Performance Perspectives. Network Compression in Domino 6"
http://www-10.lotus.com/ldd/today.nsf/aa2db969526197dd85256b56004e5a7b/1c4bc125e871f15300256c0700599ee9?OpenDocument
Supporting Information:
Additional Information on LZ1 compression in the Notes/Domino 6 help:
Lotus Notes Help:
Use LZ1 compression for attachments
With Lotus Notes 6, you can compress attachments using the Lempel-Zev class 1 (LZ1) adaptive algorithm instead of the Huffman algorithm. Because LZ1 compression can save you a considerable amount of disk space, it is favored over the Huffman method. Be aware, however, that if you are working in an environment that uses different versions of client and server software and you choose this option, the attachments are automatically recompressed on the server using the Huffman algorithm. This recompression of attachments can add significant extra time to the process.
Domino 6 Designer Help:
Use LZ1 compression for attachments
In Lotus Domino Designer 6, you can choose to compress attachments using the new LZ1 algorithm instead of the Huffman algorithm. Because LZ1 compression can be performed quickly and efficiently, it is favored over the Huffman method. However, if you are working in an environment that uses different versions of client and server software (for example, a Lotus Domino Designer 6 client and an R5 server) and you choose this option, attachments are automatically recompressed on the server using the Huffman method. Note that recompressing has performance implications. For best performance, use LZ1 in primarily Domino 6 environments.
Domino 6 Administrator Help:
Upgrading Database Format
After you install Lotus Domino 6 on
a server, you can upgrade the format of databases on that server. The database
format determines which features are available in a database. Some Domino
6 features, such as LZ1 compression and view logging, require the Domino
6 database format.
Compressing network data on a server
port
WAN connections
Enabling network compression on X.PC
ports can significantly reduce the time it takes to send and receive data
over a remote connection between a Notes workstation and a Domino server
or between two Domino servers.
You benefit from using network compression only if the data being transmitted is not already compressed. In the case of a network dialup service such as Microsoft's Remote Access Service (RAS) which includes built-in compression, enabling compression on Notes network ports does not provide any additional benefit. The same is true of tasks involving data that was compressed using the Lempel-Ziv algorithm (LZ1 compression) -- such as replicating a mail file with a large number of compressed attachments.
Database management
| New feature | Description | For more information |
| LZ1 compression for attachments | Replaces Huffman compression for file attachments. LZ1 compression is optional. It saves space by compressing attachments more efficiently than Huffman compression. | See the book Application Development with Domino Designer or the Domino Designer 6 Help. |
Database properties that optimize
database performance
Use LZ1 compression for attachments
(Note: This is exactly the same text as in the Designer 6 help,
pasted above)
In Lotus Domino Designer 6, you can choose to compress attachments using the new LZ1 algorithm instead of the Huffman algorithm. Because LZ1 compression can be performed quickly and efficiently, it is favored over the Huffman method. However, if you are working in an environment that uses different versions of client and server software (for example, a Lotus Domino Designer 6 client and an R5 server) and you choose this option, attachments are automatically recompressed on the server using the Huffman method. Note that recompressing has performance implications. For best performance, use LZ1 in primarily Domino 6 environments.
Interoperability Issues
Databases
- In Lotus Domino 6, LZ1 compression for file attachments replaces Huffman compression in Lotus Notes/Domino 5. If the LZ1 compression option is set on a Domino 6 database, a Notes 5 client will be unable to read the compression. The Lotus Domino 6 server converts LZ1 to Huffman compression for the Notes 5 client. This affects server performance. Implement LZ1 compression in an exclusively Lotus Notes/Domino 6 environment.
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