[Users] OpenVZ & Max File Descriptors

[Scott Dowdle]

Greetings,

----- Original Message -----
> I've had a problem with a service on a CT failing with "too many open
> files".
> 
> The max number of file descriptors was 1024 - I've now increased the
> max number of open files and max user processes to 65535 on the
> hardware node per the info here:
> 
> http://ithubinfo.blogspot.co.uk/2013/07/how-to-increase-ulimit-open-file-and.html
> 
> I'm running Centos v6.5 as follows
> 
> [root at machine ~]# uname -a
> Linux example.com 2.6.32-042stab084.17 #1 SMP Fri Dec 27 17:10:20 MSK
> 2013 x86_64 x86_64 x86_64 GNU/Linux
> 
> The output of ulimit -a on the hardware node is as follows:
> 
> [root at example ~]# ulimit -a
> core file size (blocks, -c) 0
> data seg size (kbytes, -d) unlimited
> scheduling priority (-e) 0
> file size (blocks, -f) unlimited
> pending signals (-i) 126948
> max locked memory (kbytes, -l) 64
> max memory size (kbytes, -m) unlimited
> open files (-n) 65535
> pipe size (512 bytes, -p) 8
> POSIX message queues (bytes, -q) 819200
> real-time priority (-r) 0
> stack size (kbytes, -s) 10240
> cpu time (seconds, -t) unlimited
> max user processes (-u) 65535
> virtual memory (kbytes, -v) unlimited
> file locks (-x) unlimited
> 
> The output of ulimit -a on the CT is the same.
> 
> Question: is this set-up 'correct' and unlikely to cause future
> issues with access to files and resources i.e. is there a danger
> that I have over-committed the server?

Since you are using the EL6-based OpenVZ kernel you have the ability to use a vswap style config for your container.  You talk about shell / account specific limit controls but not really what, if any, resource limits you have set on the container via it's OpenVZ config file.  The vswap style config generally only limits ram and vswap and sets everything else to unlimited.

To answer your question, I'm guessing you should be fine... but can any single container exhaust all of your resources?  Perhaps but I don't think it is likely with normal usage patterns.  I guess you'll just have to see how well it works for you.  There isn't one set of settings that is good for everything and everyone.

TYL,
-- 
Scott Dowdle
704 Church Street
Belgrade, MT 59714
(406)388-0827 [home]
(406)994-3931 [work]