On 02/18/12 23:39, Matthew Seaman wrote:
On 18/02/2012 11:36, Da Rock wrote:
If I may, can I ask a quick question: My main misgivings about ZFS have
been speed, ram use, and up till about a year ago or so relative 'youth'
(at least on FreeBSD). What would be the minimum ram you would use for a
high disk use? And what would be recommended to use for the caching? I
was thinking 8G ram and either a high quality usb/SD(/CF?) disk or a
sata II/III SSD for cache.
Yes -- ZFS uses RAM heavily to improve performance. I've a VM running
ZFS with only 1GB which is pretty slow. Mind you, a similar VM with
UFS is also pretty slow.
For an actual machine, about 4GB makes a reasonable ZFS system. More is
better though; 8GB is what I'd recommend. ZFS speed is on the whole
pretty reasonable. It doesn't do small, randomized IO very effectively,
so it's not ideal to run a database on. Other than that, for a home
e-mail / web /fileserver ZFS is just fine.
I haven't tried SSDs or anything like that -- that's an optimization to
improve latency when accessing lots of different files, and my usage
doesn't really justify it. Try it without before spending any money on
SSDs. It may well be good enough, but if it isn't then adding SSDs and
making ZFS use them for ZIL or cache is pretty simple (and doesn't
require any downtime.)
I was thinking along the lines of continuous heavy load of writing (some
read) rather large files (5G+ would be average - multiple!) - does that
warrant caching or is it only lots of smaller files? That and lots of
~0.5G files (read mostly) is what defines the main load on the system.
I ask because I'm not 100% sure of what the caching is for. I had
thought it was like the journal log for fast writing to be later written
to the filesystem itself, but now I think I may be wrong in my
judgement. It now sounds like a fast access for usual suspects.
Now you see how a terabyte and a half disk space can be used in a matter
of hours :)
_______________________________________________
freebsd-questions@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-questions
To unsubscribe, send any mail to "freebsd-questions-unsubscr...@freebsd.org"
