Date: Sat, 18 Feb 2012 21:36:25 +1000 From: Da Rock <freebsd-questions@herveybayaustralia.com.au> To: freebsd-questions@freebsd.org Subject: Re: /usr/home vs /home Message-ID: <4F3F8D39.80907@herveybayaustralia.com.au> In-Reply-To: <4F3F8A46.1090908@infracaninophile.co.uk> References: <4F3ECF23.5000706@fisglobal.com> <20120217234623.cf7e169c.freebsd@edvax.de> <3D08D03C85ACFBB1ABCDC5DA@mac-pro.magehandbook.com> <alpine.BSF.2.00.1202172316230.11247@abbf.6qbyyneqvnyhc.pbz> <20120218112252.772c878b.freebsd@edvax.de> <4F3F80FD.8070201@herveybayaustralia.com.au> <4F3F8A46.1090908@infracaninophile.co.uk>
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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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