From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bill Davidsen Subject: Re: Different sized disks for RAID1+0 or RAID10. Date: Thu, 11 Oct 2007 13:00:11 -0400 Message-ID: <470E569B.8060108@tmr.com> References: <470E435C.2090703@tmr.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: kbyrd-linuxraid@memcpy.com Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids Kelly Byrd wrote: > > On Thu, 11 Oct 2007 11:38:04 -0400, Bill Davidsen wrote: > >> Kelly Byrd wrote: >> >>> I've currently got a pair of identical drives in a RAID1 set for >>> my data partition. I'll be getting a pair of bigger drives in a >>> bit, and I was wondering if I could RAID1 those (of course) and >>> then RAID0 the two differently sized mds. Even better, will RAID10 >>> let me do this? >>> >>> >> RAID-10 will let you do this, read past threads of this list for >> discussion of using the "far" option to gain performance. >> >>> I don't need to grow the current RAID1 into this new beast, I've >>> got a place I can copy the existing data so I can start from >>> scratch. >>> >>> > > Doesn't the 'far' option trade write performance to gain read > performance? This is a desktop, not at all a "mostly read" type > workload. > > Is your load not read-mostly? The things I want to have happen quickly are things like boot, start application, load a document, saved page, or man page, compile a kernel (that may not be typical), play an mp3 or video, load image(s) in gimp or similar, read mail... all things which feel faster if you favor read performance. I think of it this way: most of the stuff I write is buffered by the system and I don't have to wait for it (unless it's huge). Most of the large stuff I read, as noted above, is stuff I wait for. If you look at the times you have to wait for i/o, I bet you will decide a desktop is read-mostly after all. > >>> I imagine the answer is: "sure RAID10 / RAID0 let's you do this, >>> but you don't get the striping performance benefit" for some of >>> the data", which would be ok with me until the smaller drives go >>> bad and I replace them. >>> >>> >> Replacing the smaller drives could be an adventure if you plan to go to >> larger replacement drives. I don't recall the issues involved with using >> larger partitions and RAID-10, there's another issue for you to research. >> >> > > Will do. > > > - > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- bill davidsen CTO TMR Associates, Inc Doing interesting things with small computers since 1979