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I have 2 web servers to provide PHP websites.

One server is : Apache + PHP-FPM + APC

The other : Apache with MPM-itk + APC.

For both of these servers, APC has no cache system entries but only users cache entries as you can see on the screenshot. APC with only users cache entries

APC configuration is :

apc.cache_by_default  1
apc.canonicalize  1
apc.coredump_unmap  0
apc.enable_cli  0
apc.enabled 1
apc.file_md5  0
apc.file_update_protection  2
apc.gc_ttl  3600
apc.include_once_override 0
apc.lazy_classes  0
apc.lazy_functions  0
apc.max_file_size 2
apc.num_files_hint  1000
apc.report_autofilter 0
apc.rfc1867 0
apc.rfc1867_freq  0
apc.rfc1867_name  APC_UPLOAD_PROGRESS
apc.rfc1867_prefix  upload_
apc.rfc1867_ttl 3600
apc.shm_segments  1
apc.shm_size  256
apc.stat  1
apc.stat_ctime  0
apc.ttl 7200
apc.use_request_time  1
apc.user_entries_hint 4096
apc.user_ttl  7200
apc.write_lock  1

Does anyone know why APC acts like this and how to make it work well ?

Thank you for your help!

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Please edit the solution out of your answer and post it as an answer when you get a chance, then accept it. Answering your own questions is allowed and encouraged on Stack Exchange sites, and makes it easier for future visitors to your question to quickly find the information they're searching for. – HopelessN00b Jan 23 '15 at 9:02
up vote 0 down vote accepted

I've found the problem after many tests : On one server, there is APC v3.1.3 and on the other it's v3.1.13. To make it work fine, I have to play with the "M" defining sizes (putting "M" or not), like this :

v3.1.3 :
apc.shm_size = 256
apc.max_file_size = 2M

v3.1.13 :
apc.shm_size = 256M
apc.max_file_size = 2M
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