Tuning Guidelines for fs_bufcache in 11.31

[Alzhy]

Is there one?

I've a new RX6600 - 32GB and functions as my NBU Master/Media Server.

I mount split mirror filesystems (~22TB worth) to this machine for ackup to LTO4 tapes.

I noticed my backups failed with Err 28 which is unable to fork process (lack of mem?). Looking at Glance with no more backups running fs_bufcahce is still a whopping 15GB

Glance reports 12G as system Mem, 1.6GB as User mem and 3.0G as "Free" Mem.

Any tuning advice?

This new NBU Server Master will have 10 LTO-4 Drives, 6 pairs of Gigabit network, and serving over 200 UNIX and WIndows CLients with a total backup everyweekend of over 60TB.

[Fabio Ettore]

Hi,

since fs_bufcache is the kernel module I think you refer to guidelines for filecache_max and filecache_min, which are the kerner parameters. The man of them gives advices about when tuning them.

Also see the following link which explains really well the new UFC on 11.31.

HTH.

Best regards,
Fabio

[Alzhy]

Fabio.. you missed the URL..

Anyways I've adjusted my filecache_max to just 10GB....

[Fabio Ettore · Accepted solution]

Sorry, I'm a little asleep today...
Here the link about UFC:

http://h71028.www7.hp.com/ERC/downloads/4AA0-7157ENW.pdf

Anyway I suggest taking a look especially at man pages and following sections so named:

Recommended values

Who Is Expected to Change These Tunables?

When Should the Value of These Tunables Be Raised?

When Should the Values of These Tunables Be Lowered?

What Are the Side Effects of Lowering the Values?

HTH.

Best regards,
Fabio

[Rita C Workman]

Hi Nelson,

On 11.31, fs_cache min/max replaced the old favorite dbc_min/max_%. And, as such, the new ones default settings also is similar running 50/5 for max/min.
So, like with dbc_min/max you probably need to reduce them, to alleviate some pressure.

In Stephen Cuillo's many writings he mentions that the UFS parms basically replaced the old buffer cache settings. So, just like in the old parms, try reducing these first and see if you see some memory pressure relief.

Rgrds,
Rita

[Alzhy]

Already did, thanks.

And it was easy.. and dynamic:


kctune filecache_min=10% filecache_max=30%