[OpenIndiana-discuss] SSD as a dedicated swap device

[David Brodbeck]

On Fri, Dec 11, 2015 at 5:24 PM, Reginald Beardsley via openindiana-discuss
<openindiana-discuss at openindiana.org> wrote:

> My long standing rule is swap = 8 x core.


Hmm.  I could see that working for small systems, but I have some machines
where that would require dedicating a terabyte of disk to swap.  That
doesn't seem reasonable, especially when the root partition is on an SSD
that may itself not be much bigger than core RAM.

It also never really made sense to me why you'd increase swap when you add
more RAM.  It seems like a system with more RAM would need *less* swap.

The recommendation for a while was 2 x core, but I think that stemmed
partly from Linux using a virtual memory implementation at the time that
couldn't swap properly if swap was smaller than that.  These rules of thumb
tend to start for logical reasons but then carry on as cargo cults long
after -- sort of like how I still see people setting
"rsize=32768,wsize=32768" on NFS mounts to "improve performance." :)

-- 
D. Brodbeck
System Administrator, Linguistics
University of Washington
GPG key fingerprint: 0DB7 4B50 8910 DBC5 B510 79C4 3970 2BC3 2078 D875