Date: Sun, 30 Mar 2003 10:27:03 -0500 From: Chuck Swiger <cswiger@mac.com> To: freebsd-stable@freebsd.org Cc: Lukas Ertl <l.ertl@univie.ac.at> Subject: Re: vinum performance Message-ID: <3E870CC7.5000204@mac.com> In-Reply-To: <20030330125138.K23911@leelou.in.tern> References: <20030330125138.K23911@leelou.in.tern>
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Lukas Ertl wrote: [ ... ] > I created several RAID 0 and RAID 5 volumes with different stripe sizes > and let bonnie++ run over the filesystems. I was quite disappointed about > the RAID 5 performance, and even the RAID 0 performance wasn't too good > (a plain single disk filesystem was almost as fast as or even faster than > a RAID 0 stripe, and I wouldn't expect that). > > RAID 5 performance was really a mess, some of the test took more than > 30min. to complete. There are three goals or priorities to choose from when configuring RAID: performance, reliability, and cost. What are yours? Also, what tasks you intend to use the RAID filesystem for are critical to consider, even if the answer is simply "undifferentiated general-purpose storage". In particular, RAID-5 write performance is going to be slow, even with RAID hardware support which offloads the parity calculations from the system CPU(s). RAID-5 is best suited for read-mostly or read-only volumes, where you value cost more than performance. Um, that is a dual-channel card, and you're splitting drives onto both channels, right? Anyway, if I had your hardware and no specs as to what to do, I'd probably configure 2 disks as a RAID-1 mirror for an OS boot volume; configure 4 disks as RAID-10; and use the 7th disk as a staging area, hot spare, etc. -- -Chuck
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