Date: Fri, 25 Sep 2015 10:01:18 -0400 From: Paul Kraus <paul@kraus-haus.org> To: Graham Allan <allan@physics.umn.edu> Cc: freebsd-questions@freebsd.org Subject: ZFS ready drives WAS: zfs performance degradation Message-ID: <106217D9-F3DB-4DB5-822E-098041B5BC6F@kraus-haus.org> In-Reply-To: <5605481D.10902@physics.umn.edu> 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> <2008181C-F0B5-4581-9D15-11911A1DE41B@kraus-haus.org> <CAFYkXjkdUrcUUdVQW4qgSuEmtifD=mvbvf4k0vq5t9R6dtR1pQ@mail.gmail.com> <6498A090-A2A2-4580-A148-2BCBF68BF2BF@kraus-haus.org> <5605481D.10902@physics.umn.edu>
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On Sep 25, 2015, at 9:11, Graham Allan <allan@physics.umn.edu> wrote: > On 9/24/2015 7:58 PM, Paul Kraus wrote: >> On Sep 24, 2015, at 17:40, CeDeROM <cederom@tlen.pl> wrote: >>=20 >>> For RAID/NAS use ondy WD RED drives family :-) Others WILL break >>> timings with hidden error verify mechanisms.. >>>=20 >>> http://www.wdc.com/red >>=20 >> I assume you are referring to the other =93color=94 drives. I have = had no >> issues with the RE and SE series of Datacenter drives in zpool >> configurations. >=20 > WD Reds are pretty solid, and I have used hundreds of them in ZFS = pools without *apparent* issues, while I would never consider the blue = or even less Green for this. However they're still a low-cost option - = if I'd had the funds I would much rather have used SE or RE! Your comment reminded me=85 one of the big reasons to only use = Enterprise / Datacenter / NAS rated drives for ZFS is the way the = _drive_ handles errors. Many of the consumer drives will retry a failing = READ many, many times. This _can_ lead to timeout issues in the OS and = ZFS. The reasoning here is that for a consumer, getting a good read is = worth the extra time (I have seen reports of up to 30 seconds before = giving up) because the consumer probably does not have any redundancy. = With ZFS (assuming something more than a basic stripe configuration) you = want the drive to return the read error to the OS as fast as it can so = that the OS and ZFS can deal with it. I have also used WD Green and Purple drives with ZFS, but I do not = expect Enterprise grade operation out of them. I also question the economics of the consumer drives, once you take the = 5 year warranty in account. Looking at Newegg for 2 TB 3.5=94 WD drives: Green $79 2-year Purple $85 3-year Red NAS $90 3-year Black $119 5-year SE $130 5-year Red Pro NAS $134 5-year RE $153 5-year So the premium cost for the Red NAS is $11 over the cheapest option. The premium cost for a 5-year warranty (Black, not rated for 24/7 or = NAS, a high end desktop drive) is $40. The Premium for the cheapest Datacenter drive (SE) is $51, or more than = a 50% increase in cost. But the warranty is more than twice as long = (2-year vs. 5-year). In my experience, most 5-year warranty drives fail in some way during = the warranty period. This is especially true of Seagate. On my home = system, 5 out of 6 Seagate ES.2 series drives failed within 5 years, the = last one failed within 6 months of the warranty expiration. Half of my = HGST drives have failed under warranty (so far, they have not all hit = end of warranty yet), none of my WD RE or SE series have failed, but = they are the youngest drives in my collection. So part of what I am paying for with the Datacenter drives is the = knowledge that I will NOT have to pay to replace that drive for 5 years. -- Paul Kraus paul@kraus-haus.org
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