My current fstab swap setting (by the Mandrake install) :- /dev/hda5 swap swap defaults 0 0
question - what are the "defaults" ?
Recommended setting in the article mentioned above :- /dev/hdc5 none swap sw,pri=3 0 0 /dev/hda5 none swap sw,pri=3 0 0
This should cause the system to use both in parallel because they have the same priority, and apparently go like blazes.
The "sw,pri=3" seems OK according to man swapon, but it's dated 1995.
Do these options look sane ?
thanks Rod ----------------------------------------------------------- Brought to you by a thunderbird, penguin, gnu and a camel
Roger Barnes wrote:
Hiya Rod,
1. What's the difference between "buffer-cache reads" and "buffered disk reads" ? I have 3 disks and the figures vary.. with the cache read mb figues approx. 10 times those of the disk reads. Which figure is more important re. swap ?
My understanding (which could be incorrect) is that the cached reads are testing the speed of the small bit of volatile cache on the disk (it's fast, but it's not the magnetic bit where the data lives permanently). In reality, throughput is going to be closer to the buffered disk read speed. For swap, or any purpose really, you really should benchmark something realistic and if you're that keen, you might be able to find some applications that do that. The hdparm figures are raw read speeds with and without using the disk cache respectively. For improving things in your situation, I'd suggest you just look at the "buffered disk read" speed, then see if that number improves with any tweaking you do.
2. Are you implying I can have multiple swap files actyive simultaneously ?
Certainly. Apparently linux is reasonably clever about making good use of it too. A link that I just found with a bit of googling seems worthy of a good read ...
http://www.fiveanddime.net/ss/swap.htm
Cheers, - Rog
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