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Mia_27938's avatar
Mia_27938
Icon for Nimbostratus rankNimbostratus
Feb 12, 2015

Why the images is compressed?

Hello All,

I apply the compression profile to a VS.

As far as I know, because the image was already compressed itself, they don't have to be compressed. Right?

Hmm. However the images are compressed.

So I exclude the image but they still are compressed.

I tested with two profile as follows;

ltm profile http-compression httpcompression_test_1 {
app-service none
buffer-size 40960
content-type-exclude none
content-type-include { text/ "application/(xml|x-javascript)" }
defaults-from httpcompression
min-size 512
selective enabled
uri-exclude { .*\\jpeg .*\\png .*\\gif .*\\jpg }
uri-include { .*\\html .*\\htm .*\\js .*\\css .*\\asp .*\\aspx }

}

ltm profile http-compression httpcompression_test_2 {
allow-http-10 disabled
app-service none
browser-workarounds disabled
buffer-size 40960
content-type-exclude { image/ img/ }
content-type-include { text/ "application/(xml|x-javascript)" }
cpu-saver enabled
cpu-saver-high 90
cpu-saver-low 75
defaults-from httpcompression_jobkorea_1
gzip-level 1
gzip-memory-level 8k
gzip-window-size 16k
keep-accept-encoding disabled
method-prefer gzip
min-size 512
selective enabled
uri-exclude none
uri-include { .* }
vary-header enabled

}

The images still are compressed.

Ltm::HTTP Compression Profile: httpcompression

Content Type Compression (bytes) Pre-Compress Post-Compress

HTML 495.7M 102.0M

CSS 8.6M 1.7M

JavaScript 0 0

XML 0 0

SGML 0 0

Plain 0 0

Octet Stream 138.7K 115.5K

Images 11.1M 10.2M

Video Files 0 0

Audio Files 0 0

Other 12.9M 5.4M

Total 528.6M 119.5M

NULL-Compress 0 0

Compression Ratio (%) 77.3

Am I doing something wrong? Thank you.

6 Replies

  • What happens when you dont apply these profiles to the VS?

     

    Do you also have an acceleration profile applied to your VS. Are these compressed files/images applied to the ramcache?

     

    If so, you can you delete the cache setting entries: delete ltm profile ramcache

     

    • Mia_27938's avatar
      Mia_27938
      Icon for Nimbostratus rankNimbostratus
      Hi NikhilB, Thank you for your reply. I do not use the ramcache profile. To display the following stats, I typed the command, "show ltm profile http-compression httpcompression httpcompression_test_1" Ltm::HTTP Compression Profile: httpcompression Content Type Compression (bytes) Pre-Compress Post-Compress HTML 495.7M 102.0M CSS 8.6M 1.7M JavaScript 0 0 XML 0 0 SGML 0 0 Plain 0 0 Octet Stream 138.7K 115.5K Images 11.1M 10.2M Video Files 0 0 Audio Files 0 0 Other 12.9M 5.4M Total 528.6M 119.5M NULL-Compress 0 0 Compression Ratio (%) 77.3 whenever I refresh the command, "show ltm profile http-compression httpcompression httpcompression_test_1", the counts of Images is increasing. And I have been checked the HTTP response header for GIF files applied the VS with httpcompression_test_1 profile or httpcompression_test_2. As a results, the http response headers for GIF image files have Content-Encoding:gzip. This mean that the GIF images is compressed. Right? Thanks again for being with me.
    • NikhilB's avatar
      NikhilB
      Icon for Employee rankEmployee
      Is your URL list and include list empty? I would try and change the minimum content length to a value greater than the default or (larger the files that are actually being compressed) If the pre and post compress stats are different and are changing as a client hits the VS, then it prob is being compressed.
  • NikhilB_149913's avatar
    NikhilB_149913
    Historic F5 Account

    What happens when you dont apply these profiles to the VS?

     

    Do you also have an acceleration profile applied to your VS. Are these compressed files/images applied to the ramcache?

     

    If so, you can you delete the cache setting entries: delete ltm profile ramcache

     

    • Mia_27938's avatar
      Mia_27938
      Icon for Nimbostratus rankNimbostratus
      Hi NikhilB, Thank you for your reply. I do not use the ramcache profile. To display the following stats, I typed the command, "show ltm profile http-compression httpcompression httpcompression_test_1" Ltm::HTTP Compression Profile: httpcompression Content Type Compression (bytes) Pre-Compress Post-Compress HTML 495.7M 102.0M CSS 8.6M 1.7M JavaScript 0 0 XML 0 0 SGML 0 0 Plain 0 0 Octet Stream 138.7K 115.5K Images 11.1M 10.2M Video Files 0 0 Audio Files 0 0 Other 12.9M 5.4M Total 528.6M 119.5M NULL-Compress 0 0 Compression Ratio (%) 77.3 whenever I refresh the command, "show ltm profile http-compression httpcompression httpcompression_test_1", the counts of Images is increasing. And I have been checked the HTTP response header for GIF files applied the VS with httpcompression_test_1 profile or httpcompression_test_2. As a results, the http response headers for GIF image files have Content-Encoding:gzip. This mean that the GIF images is compressed. Right? Thanks again for being with me.
    • NikhilB_149913's avatar
      NikhilB_149913
      Historic F5 Account
      Is your URL list and include list empty? I would try and change the minimum content length to a value greater than the default or (larger the files that are actually being compressed) If the pre and post compress stats are different and are changing as a client hits the VS, then it prob is being compressed.