Date: Tue, 22 Apr 2014 20:45:59 -0500 From: Adam Vande More <amvandemore@gmail.com> To: Adam Vande More <amvandemore@gmail.com>, David Wolfskill <david@catwhisker.org>, Louis Kowolowski <louisk@cryptomonkeys.org>, hackers@freebsd.org Subject: Re: Pointer to info on migrating from UFS2 -> ZFS? Message-ID: <CA%2BtpaK2TGYsrNjnOaqH-6RQteKKnw2X2ihjfJWWbCoiZVxGZ4w@mail.gmail.com> In-Reply-To: <20140423010417.GH43976@funkthat.com> References: <5355E9F9.5080401@freebsd.org> <63190425-672D-4A05-AAB0-B19A49EDB739@cryptomonkeys.org> <20140422222525.GR1321@albert.catwhisker.org> <CA%2BtpaK1tYvTOGRtjdsHzr595OSofiuyZgALoXZpoynUzK8zO%2Bw@mail.gmail.com> <20140423010417.GH43976@funkthat.com>
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On Tue, Apr 22, 2014 at 8:04 PM, John-Mark Gurney <jmg@funkthat.com> wrote: > Adam Vande More wrote this message on Tue, Apr 22, 2014 at 19:50 -0500: > > On Tue, Apr 22, 2014 at 5:25 PM, David Wolfskill <david@catwhisker.org > >wrote: > > > > > I appreciate the responses, but I seem to have failed to communicate at > > > least a couple of fairly important aspects of what I'm trying to do. > > > So.... > > > > > > On Mon, Apr 21, 2014 at 06:40:05PM -0700, Louis Kowolowski wrote: > > > > I?d probably suggest a couple things: > > > > * VirtualBox (or equiv) for setting up test environments that are > easy > > > to create and destroy. For all the beginning stuff I can think of, you > > > should be able to do just fine with a virtual environment. VMs with a > half > > > dozen virtual disks that are 2G ea come in handy with playing with ZFS. > > > > > > I have existing hardware -- several instantiations of it, including a > > > couple of test machines. I am trying to find out if the use of ZFS > (vs. > > > UFS2+SU) on the existing hardware will provide a performance advantage > > > (and if so, how much, as switching from UFS2 to ZFS is going to be > > > extremely painful). > > > > It's very difficult to make any detailed concise comment since we know > > virtually nothing about your hw or workload. What do you need? More > iops? > > Then use a ZIL (maybe even a battery backed DDR drive) to increase > writes, > > But that is only for sync writes, which are for things like fsync... > ZFS write delays writes for vfs.zfs.txg.timeout seconds and combines > them into transaction groups, so unless you're running a db that does > fsync or an NFS server, a ZIL probably won't help you as much as you > think it will... Obviously benchmark your use case w/ and w/o ZIL... > > > and lots of RAM and cache device to increase read speed. When I had this > > setup, diskinfo run on VM's backed by ZVOL's would reflect SSD, not 7200 > > spinning media speeds. > > > > Also things like transparent compression can help certain workloads > > tremendously. If you're dealing with 99% text data by compressing the > data > > you effectively drastically lower the iops needed to work the data and > > off-load the work to the CPU's which are obvious a lot faster than disk. > > > > There are also a lot of different RAID(z) qualities so care should be > taken > > when choosing layouts. > > Yes, it should be... remeber that raidz is closer to RAID3, than RAID5 > in terms of IOPS, but doesn't suffer the read-modify-write issue that > RAID5 has... So you won't necessarily get the same IOPS from a raidz > config as you would from a hardware raid5 system... > > -- > John-Mark Gurney Voice: +1 415 225 5579 > > "All that I will do, has been done, All that I have, has not." > For even more raid5 fun, check out a "punctured stripe". -- Adam
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