Date: Thu, 11 Feb 1999 09:40:11 +1030 From: Greg Lehey <grog@lemis.com> To: Brad Knowles <brad@shub-internet.org> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: Software RAID-5 comparison: FreeBSD 3.0 vs. Solaris 2.6/x86... Message-ID: <19990211094011.J71962@freebie.lemis.com> In-Reply-To: <19990210201901.026071@relay.skynet.be>; from Brad Knowles on Wed, Feb 10, 1999 at 08:19:01PM %2B0100 References: <19990210201901.026071@relay.skynet.be>
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On Wednesday, 10 February 1999 at 20:19:01 +0100, Brad Knowles wrote: > Folks, > > I'm in the process of setting up a new anonymous ftp server for the > ISP that I work for, and I'm wondering if you might be able to give me > some advice. > > Specifically, I have currently chosen to go with Solaris 2.6/x86 + > Solstice DiskSuite 4.1 (RAID 5) + UFS logging. > > Among other things, this gives me a log-structured filesystem so that > I never have to fsck /export/home/ftp, We don't have that yet. > the DiskSuite tools let me grow the filesystem while it's online > (and it doesn't have to be blown away and re-newfs'ed), That's in the pipeline, but it's not there yet. > and there are some pretty cool performance monitoring tools > available from Rich Petit (SymbEL 3.x) and Adrian Crockcraft (author > of the book _Sun Performance and Tuning: Java and the Internet_). And we don't have much in that area either. Vinum maintains a number of statistics, but that's about all. > Now, I can't change the hardware (400Mhz Intel Pentium II w/ 256MB > RAM, internal Western Digital 4.3GB UltraSCSI2 HD, Adaptec 3940UW SCSI > controller, five Quantum 9GB and four Western Digital 9GB UltraSCSI2 > drives). The two sets of SCSI disk drives are mounted as two separate > filesystems. > > However, if there were likely to be a significant performance > increase with FreeBSD 3.0 + vinum + softupdates, I'd seriously consider > switching (although I'd still want to try to find some decent performance > monitoring tools, hopefully as good as SymbEL 3.x). What I've been seeing with Vinum is that it loses about 2-5% performance on concatenated volumes, and gains up to 45% on a two-way striped volume. My tests weren't primarily for performance, and they included a lot of debug aids, so a well-tuned Vinum system would probably be pretty transparent. I'd guess that Sun's tools are pretty close to that. There's no magic involved. > At the moment, I'm not interested in running these drives in pure > striping mode. The machine isn't *that* important to us and our > customers that we need a hardware RAID controller, but whereas you could > probably get away with just striping a news server, I think the downtime > on a system-wide ftp server would probably not be acceptable. > > If anyone can provide alternative arguments to this position, I'd > love to hear them. > > One thing I do know (from scouring previous posts to this mailing > list, as well as previous posts to news.software.nntp), is that you want > to set the stripe size as large as you feasibly can, so that any file > access is highly likely to hit only one disk at a time, thus allowing > multiple simultaneous disk accesses to be relatively evenly spread over > all drives that are available. Correct. This applies to the Sun implementation as well. > Is there anything else I should know? Probably, but I can't think of anything to volunteer. Greg -- When replying to this message, please copy the original recipients. For more information, see http://www.lemis.com/questions.html See complete headers for address, home page and phone numbers finger grog@lemis.com for PGP public key To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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