Controlling autosize threshold

[kevin_graham]

Is there a way to control when FlexVol autosize is triggered? The documentation states that its when a volume is "about to run out of free space". However, once its crossed 95%, someone has already gotten woken up in the middle of the night and isn't about to trust that Magic Things Will Happen if free space falls any lower.

As-is, it seems to be a nice last-ditch effort, but I'd like to be able to set a threshold (~85-90%) for autosize to kick in to ensure that there's no false sense of security once utilization has started creeping way up and that its clear something really must be done to provide more space.

[diarmuidn]

In priv set diag and you can reset the wafl_reclaim_threshold figure values using the 'setflag' command.

eg: setflag walf_reclaim_threshold_t = 96

(note: there are 5 values.. _t, _s, _m, _l, _xl. There represents tiny, small, medium, large and extra large volumes)

Use the printflag option to view current values

[jimmcclung]

Can anyone provide what values constitute the various categories tiny, small, medium, large and extra large?

What I mean here is my 8 TB volume is an _xl volume. Into which category does an 100 GB volume fall? Or a 10 GB volume?

[pascalduk]

I have the following list, but unfortunately I can't find the netapp source document anymore. It probably was in one of the tr's.

Volume size	Trigger point
< 20 GB	85%
20 - 100 GB	90%
100 - 500 GB	92%
500 GB - 1TB	95%
> 1TB	98%

[jimmcclung]

Pascalduk nailed the answer to my question. Thanks!

[radek_kubka]

Use the printflag option to view current values

To make it more fun, the output is actually in hex :

fas01*> printflag wafl_reclaim_threshold_t
wafl_reclaim_threshold_t = 0x55
fas01*> printflag wafl_reclaim_threshold_s
wafl_reclaim_threshold_s = 0x5a
fas01*> printflag wafl_reclaim_threshold_m
wafl_reclaim_threshold_m = 0x5c
fas01*> printflag wafl_reclaim_threshold_l
wafl_reclaim_threshold_l = 0x5f
fas01*> printflag wafl_reclaim_threshold_xl
wafl_reclaim_threshold_xl = 0x62

[radek_kubka]

Also, changing thresholds via setflag is non-persistent & everything will change to the default values after reboot.

To make it persistent the applicable line(s) should be added to /etc/rc file on both controllers, e.g.:

priv set diag;setflag wafl_reclaim_threshold_xl 0x63;priv set

[jimmcclung]

Thanks for the follow up!

[henrypan1]

Radek,

I was wonder whether there is anything new in control autosize?

Thanks

Henry

[radek_kubka]

Hi Henry,

I haven't come across anything new re autosize control - but maybe some NetApp insiders will chime in & tell us what's new or in the pipeline?

Arguably the method we know is a bit, hmm, clunky

regards,

Radek

[wmulhair1]

Adding my voice to this.  Since our monitoring triggers alerts at 90% for any volume which results in somebody being paged in the middle of the night I'd rather have all volume autosizes triggers at 90% and respond to why the volume grew in the morning.