RE: Linux buff/cache memory too high when running Archiver Appliance

[Abdalla Ahmad via Tech-talk <tech-talk at aps.anl.gov>]

Hello Lin

 

Maybe it has something to do with Debian? The main AA server is a 7-year-old server running CentOS 7.4 with 20 cores 128GB and archiving +17K PVs, 24GB used with 100 GB buff/cache and the new server with the same PV list and archived data size is running on a Rocky Linux 8.6 VM with 4 cores and 64 GB RAM, 14 GB is used and 50 GB is buff/cache. We never noticed performance issues even with such large buff/cache values, even on data retrieval with large timestamps.

 

Best Regards,

Abdalla.

 

From: Tech-talk <tech-talk-bounces at aps.anl.gov> On Behalf Of Wang, Lin via Tech-talk
Sent: Monday, February 5, 2024 6:11 AM
To: tech-talk at aps.anl.gov
Subject: Linux buff/cache memory too high when running Archiver Appliance

 

Dear all,

 

In our Debian 10 environment, when Archiver Appliance runs for quite a while, the buff/cache memory will become very high. For example, in the virtual machine with 64GB memory, when Archiver Appliance is up for 14 days, 24GB memory is used, whereas 39GB memory are buff/cache and there is only 400MB free memory left as follows.

 

MiB Mem :  64422.7 total,   398.7 free,  24700.1 used,  39323.9 buff/cache

MiB Swap:   7629.0 total,   6227.7 free,   1401.2 used.  38838.9 avail Mem 

 

Probably it is not a problem since Linux buff/cache will be freed when other applications need memory. However when buff/cache is too high and free memory is too low, the whole Linux OS seems to be very slow.

 

I would like to hear about experiences from other sites. Is it necessary to deal with this situation or not? If yes, what is the recommended way to reduce or clear the buff/cache memory?

 

 

Thanks,

Lin