Date: Thu, 24 Sep 2015 14:37:56 -0400 From: Paul Kraus <paul@kraus-haus.org> To: Dmitrijs <war@dim.lv> Cc: FreeBSD Questions <freebsd-questions@freebsd.org> Subject: Re: zfs performance degradation Message-ID: <2008181C-F0B5-4581-9D15-11911A1DE41B@kraus-haus.org> In-Reply-To: <56042209.8040903@dim.lv> References: <56019211.2050307@dim.lv> <37A37E9D-9D65-4553-BBA2-C5B032163499@kraus-haus.org> <56038054.5060906@dim.lv> <782C9CEF-BE07-4E05-83ED-133B7DA96780@kraus-haus.org> <56040150.90403@dim.lv> <60BF2FC3-0342-46C9-A718-52492303522F@kraus-haus.org> <560412B2.9070905@dim.lv> <8D1FF55C-7068-4AB6-8C0E-B4E64C1BB5FA@kraus-haus.org> <56042209.8040903@dim.lv>
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On Sep 24, 2015, at 12:17, Dmitrijs <war@dim.lv> wrote: > I also get about 60-70MB/sec via CIFS or ftp, but my aim is to be = limited by network, so 100MB is wanted.=20 It=92s nice to want things. But be prepared to pay for the things you = want... > Or, to understand why it is not possible on my config :) > But simple dd of=3D/dev/null in the console shows me 110MB/sec=85 dd of anything, but especially of /dev/null is a very poor way of = measuring anything. Turn on compression and and do that test again. > iozone gives me the same 100+Mb/sec both on read and write. What size blocks ? Files ? Random or sequential I/O ? All that matters. > 2x HGST HDN724040ALE640, 4Tb, 64Mb, 7200. Consumer NAS drives=85 I have not purchased anything but an Enterprise = drive for close to 10 years now. The small additional cost is well worth = the longer (5 year) warranty and better build quality=85 there _is_ a = difference. Even looking at the specs, the uncorrectable error spec is a = very good indicator of build quality and these drives are typical 1 in = 10^14 consumer drives. Enterprise drives are typically an order of = magnitude better, 1 in 10^15. In your original post you mentioned WD Green drives, also consumer = grade. In my experience I have seen better performance from WD than = HGST, with Seagate at the bottom of the ladder. I was comparing all = Enterprise drives, and even among those offerings there are differences=85= the WD RE are noticeable faster than the SE. I look at svc_t as the = primary metric for _comparing_ drives. I create a simple striped zpool, = reboot the system to clear counters, then do _lots_ of (typically) = random I/O, then look at iostat -x and compare svc_t, lower numbers are = better. I generally don=92t buy matched drives for mirrors, but different makes = and models if I can. That way of there is a bad production run I don=92t = lose all my drives at once. When a drive fails I RMA it under warranty = and buy 2 more of the same type and capacity, one goes into the server = and the other sits on the shelf. Eventually I have enough drives to grow = the zpool and move on. > For example, yesterday I explored QNAP TS-451 > official site: = https://www.qnap.com/i/en/product/model.php?II=3D143&event=3D2 (Intel=AE = Celeron=AE 2.41GHz dual-core processor, 1GB DDR3L, etc) > and review: http://www.storagereview.com/qnap_ts451_nas_review > 473euro They _might_ be fine products, But I don=92t trust my data to = appliances. _I_ want to control the redundancy. > Promised performance of the models is about 100Mb/sec, even up to = 200Mb/sec but ok, it's marketing and pretty diagrams ;) And all the tests were probably done on empty (to start) volumes. You = can achieve similar numbers with ZFS with similar hardware and LOTS of = parallel clients. -- Paul Kraus paul@kraus-haus.org
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