/usr/home vs /home
Da Rock
freebsd-questions at herveybayaustralia.com.au
Sat Feb 18 11:41:14 UTC 2012
On 02/18/12 21:23, Matthew Seaman wrote:
> On 18/02/2012 10:44, Da Rock wrote:
>> I have yet to try ZFS (lack of resources really), but when I can I will
>> setup a SAN and it will be interesting to see how this works and I
>> probably will use a single partition. But for the general filesystem I
>> doubt a single partition will cut it (I could be a stick in the mud
>> though :) ), and I highly recommend this path for the new user;
>> especially using a desktop.
> Your statement here makes some assumptions about the way ZFS works which
> aren't the case.
I don't think I'm making as much sense as I think I am - I must be
really tired :)
Thats not what I was actually saying. My point was I know ZFS is very
different, but something like UFS isn't really up to a single partition.
> ZFS doesn't have partitions in the sense of areas of disk space reserved
> for a particular filesystem.
>
> It has two concepts: the zpool and the zfs.
>
> The zpool is about the collection of hardware used to provide the disk
> space. This incorporates all of the ideas about mirroring or RAIDZx or
> log devices of various types or spare drives. (Essentially what you'ld
> otherwise get from a very expensive raid controller.)
>
> The zfs is a chunk of filesystem namespace designated for a specific
> purpose. You can use a zfs as a raw partition, but it is very much more
> common for it to be used as a filesystem.
>
> zfses look quite a lot like partitions, but they are really quite
> fundamentally different. The basic storage unit used by ZFS is a 128kB
> block. The blocks used by a particular zfs can appear anywhere on the
> zpool, and unless the ZFS has been administratively limited to a
> particular size, the free space available to the zfs is exactly the free
> space available on the entire zpool.
>
> Looked at that way, you can see it as essentially one big partition
> spanning the entire zpool.
I've been idly looking through ZFS concepts for a little while now, but
not all of it has sunk in yet. I was going to just jump when I could and
see what hot water I dropped in and learn to swim really quick :)
How you have described it here has cleared a couple of foggy points for
me. Cheers, I owe you a beer ;)
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.
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