Morten Bjørnsvik wrote:
From: Verner Kjærsgaard [mailto:vk@os-academy.dk] | |Michael Folsom skrev: |> Hi: |> |> Quick question - what are the advantages of ZFS over XFS? |> |> I'm not trying to start a flame war but as a happy XFS user wonder |> what ZFS has to offer> | |I really don't know, if any? Are they not two different beasts? |I tried looking for info about XFS, any good links, homepage?
Please compare apples to apples. XFS represents just a subset of ZFS.
XFS is a high performance filesystem, fast lookup, fast write. Decent delete. a single volume, nothing more. SGI made XLV as a volume manager on top (unfortunately not open-sourced). Later they made XVM which is a mutli-host clustered version, still using XFS or CXFS (XFS + cluster metadata management)
In linux-world we usually use the crippled minimal feature LVM volume-manager, but it lacks almost every feature except mirroring and striping.
Those aren't LVM functions those are RAID -- even on HP-UX, IRIX, AIX and Solaris. LVM is management of disk blocks and the ability to re-assign to different LOGICAL volumes regardless of physical partition or location within different partitions.
XLV on irix had excellent realtime and striping features to really get the best performance out of your array of disks. But it lacked support for fixing stripe holes and had long revive times before you could start using your volume.
ZFS is filesystem and volumemanager. I do not know about performance (Sun claims each volume is independently threaded), but it has the most elegant management I've seen. You can easily manager 100's of disks on a very few controllers. See the Sun X4500 which has 44 disks on 8 port sata marvell sata controllers.
ZFS's volume manager has lots of features, disks are ready to use once they are connected (thus lower performance due to revive), you can move volumes back and forth, create stripes, create arrays, hot spares, encrypt etc. It is actually a very advanced software raid controller.
Last time I tested opensolaris I could not use zfs on the rootfs, it also lacks splitting volumes.
Nowadays a 1TB disk or 2x1TB mirror which you can mirror via LVM or a cheap hardware raid with 5 disks take away most of the need for a disk volume-manager. -- MortenB
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