I have been testing Notes 7.0.1 (currently we are on Domino 5, but will be upgrading soon) and I’ve been trying to test the LZ1 compression, I’ve enabled it on my mail file - this mail file is on a test 7.0.1 server - but when I add attachments in 7.0.1, and then add the same attachment to an old 5.0.13 mail file I see no big differences in the size of the attachment.
Am I missing something here?
Subject: LZ1 Compression
i dd the same testing. I was expecting a big difference in email size. I barely noticed any diferences and was very dissapointed. I used zip, excel, bmp, txt, pdf, nsf and got nothing to minimal results. I recall reading articles about lz1, should make a major impact. I saw nothing.
From 7.0.2 client i sent tests messages to inotes5 / r5 client. inotes6 users with 6.5.5 client.led on 7.02 mailfile and inotes6 mail file.
lz1 was enabled on my 7.0.2 client and inotes6 mail file.
I contaced IBM and spoke with developers at lotusphere. The response was where did you read those articles about major differences between hoffman and lz1 .
Subject: RE: LZ1 Compression
Hi Ken,
Zip files cannot be compressed another time.:
Network compression in Domino 6
Network compression cannot further compress an already compressed attachment. This includes files compressed by Notes when attached (Huffman or LZ1 attachment compression) or in a compressed file format (such as a zip archive or jpeg). In other words, once a file attachment is compressed, it can’t be further compressed by network compression.
For one of our clients, we did some testing back in 2003, here’s a screen shots abou the network usage. Globally, there was a gain,
Subject: RE: LZ1 Compression
Well I’m pretty sure that LZ1 compression was one of the big announcements when 6 was unveiled.
Presonally I have tried word doc’s, text doc’s etc - so files which are not already compressed in some way - and there is very little difference in the results when using LZ1.
Its a bit of a disappointment, but okay we’ll live with it.
Subject: RE: LZ1 Compression
Hi Murray,
are you comparing the size of the mail file , at the document level?
Or are you comparing it over network usage when you look in the log.nsf?
JYR
Subject: LZ1 Compression
it depends on the attachment, txt atts will get compressed better.Anyway LZ1 is not a strong compression method, and if you are accessing this DB from R5 or from the Web then the server will need to decompress this file in these cases each time the file is requested, so you will gain in bandwidth in some cases, but the server CPU usage will get increased.
You can use a compression tool like ZipMail (www.notes-compression.com)
HTH
Subject: Some actual numbers… (re: LZ1 Compression)
LZ1 is much better compression than Huffman. Obviously the file itself has to be compressible to have a meaningful difference:Zips are obviously already compressed, as are many image file types.
OpenOffice Writer docs (at least from 2.x) are really zip files, so there shouldn’t be a difference between LZ1 and Huffman on those
Word documents and Notes databases fall into a bit of a grey area, as each can be thought of as a container for the purposes of compression. If the contents within the container are largely images, then they won’t compress well. Consequently, sometimes they’re compressible, other times not.
Therefore, when testing the difference between Huffman and LZ1, it’s important to also use another compression utility alongside to serve as a indicator of whether a file will compress with LZ1 or not. Create a RAR, or Zip, or 7zip, or gzip or whatever your favourite happens to be. Point is determining whether the file is a decent candidate for compression.
OK, enough generalities, here are some numbers (all file sizes in bytes):
Description
File name
File size
Huffman
LZ1
Zip
Lotus Notes and Domino 7 Enterprise Upgrade Best Practices (Redbook)
redp4120.pdf
7,830,297
7,824,968
0.07%
7,611,518
2.79%
7,374,816
5.82%
Domino 7 Performance Tuning Best Practices to Get the Most Out of Your Domino Infrastructure (Redbook)
redp4182.pdf
2,649,769
2,640,242
0.36%
2,527,551
4.61%
2,405,439
9.22%
Lotus Domino 7 Application Development (Redbook)
redp4102.pdf
3,390,361
3,384,888
0.16%
3,268,957
3.58%
3,136,940
7.47%
Domino Web Access Template (Notes 6.5.4)
iNotes6.ntf
13,631,488
9,157,831
32.82%
5,701,051
58.18%
3,488,421
74.41%
OpenNTF Mail Experience (Release 7.0.2b HF1)
ONTF_dwa702b
_hf1.ntf
20,709,376
13,075,803
36.86%
8,425,127
59.32%
4,758,470
77.02%
Notes:
as noted above, all file sizes listed in bytes
percentage values in the compression columns represent the “savings” as compared to the original file size
Huffman and LZ1 numbers retrieved from Document Properties - Fields tab. Look for $File items, and scroll within them to find “Object Length”. “Compression Type” is also listed there, so this procedure also confirms which of the two was actually used by the Notes client.
Zip files created with WinZip 9.0 SR1, “normal” compression. Maximum would have yielded smaller files, but that wasn’t really the point of this exercise.
So, as those numbers demonstrate, LZ1 does make a significant difference compared with Huffman. The size of the difference depends on the source file of course. If the file can be compressed well, LZ1 makes a drastic difference in byte savings. Even if the file doesn’t compress very well, such as the PDFs above, the difference in percentage terms is huge. Especially when added up through an organization.
(edited to fix a typo, and to reformat the table a bit…)
Subject: *Excellent post!
Subject: RE: *Excellent post!
Hi,
Also,Upgrading to Domino 6:Performance Benefits
P.45 , Compression results for common file types
It’s for R6 but it may be similar for R7…and R8:-)
http://www.redbooks.ibm.com/redpapers/pdfs/redp3634.pdf
JYR
Subject: LZ1 Compression
Hi,
What Is LZ1 Compression in Notes/Domino 6.x?
It depends also of the type of attachments.
JYR