Date: Mon, 21 Jul 2014 14:44:48 -0400 From: Paul Kraus <paul@kraus-haus.org> To: questions@freebsd.org Subject: Re: deciding UFS vs ZFS Message-ID: <B128508A-8830-4D36-B4AD-E285BDF9D5BC@kraus-haus.org> In-Reply-To: <20140713190308.GA9678@bewilderbeast.blackhelicopters.org> References: <20140713190308.GA9678@bewilderbeast.blackhelicopters.org>
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On Jul 13, 2014, at 15:03, Michael W. Lucas <mwlucas@michaelwlucas.com> = wrote: > My virtualization system runs KVM, so I use UFS on VMs. Restoring > ZFS disk images via dd can be problematic. I use ZFS for the host and (generally) UFS on the guests. By using one = ZFS dataset per VM and taking frequent (hourly) snapshots I have an easy = way to roll a VM back to a stable state. > For larger boxes running on real iron, I use ZFS. >=20 > But there's a whole range of conditions between these two. And the way > to fill in the gray spaces is to ask. >=20 > So, how do you decide to use which filesystem? I think this decision tree breaks in a number of ways :-)=20 Desktop vs. Server is the first=85 In my world physical servers get ZFS for all of the various reasons = others have points out, but the biggest is the ensured data integrity. = While not perfect (nothing is), it is much closer than any other open = source solution at this point. I generally do not run FreeBSD as a Desktop (nor OmniOS or SmartOS), so = I don=92t have a strong answer for the Desktop case. Once you go down the Server branch there are more branches=85 Physical vs. Virtual I already stated that I like ZFS on physical hardware. ZFS gives me many = handles to tune (almost too many), between: basic vdev layout and configuration: mirrors, raidz<n>, how many vdevs, = etc. compression: I have seen compression make a 5 fold increase in = performance, I have also seen it reduce performance, it all depends on = your work load, CPU horsepower, and memory bandwidth. dedupe: for certain very specific workloads it can make a huge = improvement, for all the others it generally causes more trouble than it = is worth default block size: this one generates more debate than all of the = others combined, suffice it wo say, test with *your* data and choose = wisely L2ARC and ZIL devices: lots more misinformation out there; mirroring = L2ARC is only occasionally of benefit, ZIL *must* be mirrored, but only = benefits SYNC writes. Know your workload and adjust accordingly. For Virtual systems I have used both (ZFS and UFS) and have had no real = negative (or positive) experiences. Then you get into the Type of Server (be it physical or virtual): End User Mail servers (IMAP, etc.) represent a very different workload = than traditional DB servers, but I still like ZFS for the ease of = management and tune-ability. NOTE: I spent over 10 years managing Solaris systems and storage and ZFS = was a welcome change that greatly simplified storage management =85 at a = cost. I had many more ways to recover a SLVM/UFS filesystem than I do a = ZFS dataset. Part of that is maturity, when ZFS is as old as UFS I=92m = sure it=92ll be there too :-=3D) -- Paul Kraus paul@kraus-haus.org
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