Date: Tue, 14 Jun 2005 10:51:00 -0700 From: "D. Goss" <lists@dylangoss.com> To: Wojciech Puchar <wojtek@tensor.3miasto.net>, FreeBSD questions <freebsd-questions@freebsd.org> Subject: Re: 36.4GB drive formats out to 32.8GB? what am I missing please grep sectors /var/run/dmesg.boot Message-ID: <C4C71B55-ACDA-4F89-A4FF-0F901B66CA4C@dylangoss.com> In-Reply-To: <Pine.NEB.4.62.0506141744001.18067@chylonia.3miasto.net> References: <1122F428-95E6-4680-AB38-86A5A5B0F91A@dylangoss.com> <Pine.NEB.4.62.0506141744001.18067@chylonia.3miasto.net>
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On Jun 14, 2005, at 8:48 AM, Wojciech Puchar wrote: > > think twice before making RAID-5 array. are you sure small writes > will not be too common? No, you are on to something - I will be making small writes / parity calculations. This is going to be a web server but it is for clients and they do have sites running with SQL backends and not just static HTML content. > i think buying 4 80GB FAST IDE/SATA drives and arranging it as > RAID-10 will give you 160GB of FAST and protected storage. > performance gain using mirror+strip will likely offset this of > using faster 15k rpm drives. > > and it will be for sure cheaper. you may put 6 drives (RAID-10) and > even larger drives and still have cheaper alternative and even > faster. and MUCH more space. Sure, it will be cheaper. For me it's too late, I've purchased the 4 x SCSI 15k drives I need for this project. I have bought mostly unopened, in-box but secondhand IBM drives/sleds. They are still expensive but certainly not the (what I consider) insane prices for the same drives IBM direct. I'm paying around 1/3 of "list". I'm curious as to if you're right, I'll certainly have something to run some benchmarks on soon. Keep in mind this is all running though hardware raid (IBM ServeRAID 6i). Somehow I feel that 15k SCSI on U320 being processed as RAID-5 with this card will be better than you state. You're right, it will have cost more than IDE but I wanted to give this approach a try. Worst thing is that I can fall back to SCSI 1+0 as you suggest at the cost of one drive's space. My guess is that while the drives are clean I will play with both structures for the RAID and compare some benchmarks to give me an idea of what kind of hit the parity is costing me. Thanks for you comments. d.
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