From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Tokarev Subject: Re: Recommendations for RAID setup needed Date: Fri, 18 Sep 2015 14:25:37 +0300 Message-ID: <55FBF4B1.6060501@msgid.tls.msk.ru> References: <55F85E9F.1070100@youngman.org.uk> <55F8D01C.5040106@websitemanagers.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Alex , Adam Goryachev Cc: Wols Lists , Linux RAID List-Id: linux-raid.ids 16.09.2015 18:53, Alex wrote: [] >>> All four are WD30EFRX-68EUZN0. They're not the cheapest WD disks, b= ut >>> they're also not the ones with the 5yr warranty. The last array I >>> built using disks with 5yr warranty exceeded their capacity before = the >>> warranty expired. >> >> Umm, 1st google result showed this: >> http://community.wd.com/t5/Desktop-Mobile-Drives/New-WD30EFRX-Red-Dr= ive-Idle3-Timer-Set-to-8-Seconds-High-LCC-in/td-p/648821/page/5 >=20 > I was really just looking for general input on RAID5 vs RAID6, but > that is good information. I knew the drives weren't basic desktop > drives and would be generally suitable for building a software RAID > array. >=20 > Are you familiar with the idle3 time? It appears the idle3-tools can > be used to disable the idle3 timer entirely, which would disable > parking the head at all, correct? An addition. From hdparm(8) manpage: -J Get/set the Western Digital (WD) Green Drive's "idle3" = timeout value. This timeout controls how often the drive pa= rks its heads and enters a low power consumption state. The = factory default is eight (8) seconds, which is a very poor cho= ice for use with Linux. Leaving it at the default will result i= n hun=E2=80=90 dreds of thousands of head load/unload cycles in a ver= y short period of time. The drive mechanism is only rated for = 300,000 to 1,000,000 cycles, so leaving it at the default could= result in premature failure, not to mention the performance imp= act of the drive often having to wake-up before doing routine I/= O. WD supply a WDIDLE3.EXE DOS utility for tweaking this s= etting, and you should use that program instead of hdparm if at a= ll pos=E2=80=90 sible. The reverse-engineered implementation in hdparm= is not as complete as the original official program, even tho= ugh it does seem to work on at a least a few drives. A ful= l power cycle is required for any change in setting to take = effect, regardless of which program is used to tweak things. A setting of 30 seconds is recommended for Linux use. Pe= rmitted values are from 8 to 12 seconds, and from 30 to 300 seco= nds in 30-second increments. Specify a value of zero (0) to = disable the WD idle3 timer completely (NOT RECOMMENDED!). Thanks, /mjt -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html