Date: Thu, 22 Aug 1996 16:50:50 -0500 (CDT) From: Joe Greco <jgreco@brasil.moneng.mei.com> To: michael@memra.com (Michael Dillon) Cc: craigs@OS.COM, freebsd-isp@FreeBSD.org Subject: Re: Anyone using ccd (FreeBSD disk striper) for news Message-ID: <199608222150.QAA25222@brasil.moneng.mei.com> In-Reply-To: <Pine.BSI.3.93.960822125042.14970G-100000@sidhe.memra.com> from "Michael Dillon" at Aug 22, 96 12:56:28 pm
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> On Thu, 22 Aug 1996, Craig Shrimpton wrote: > > > Is anyone using the disk concatenator for FreeBSD on a news spool? It looks > > like it can dramatically increase performance but seems a little "hairy" to > > setup. > > I'd like to know this too because I'm going through an exercise right now > helping a provider build a more stable and effective fullfeed news server > than what they have. The cost of RAID is a bit steep for this provider and > as a result we've been leaning towards Linux with md. You don't want RAID that mirrors or does parity, you just want striped disks for a news operation, and ccd does it just fine. Avoid Linux unless you are prepared to play the Incompatibility Game and Kernel-Of-The-Day Game. I've been running news on every release of FreeBSD since 2.0R and haven't run into any catastrophic problems that prevent operation. Your only other _good_ choice for news, if you don't do BSD, is Solaris on a SPARC, and that has its own deficiencies. > There are a few things about FreeBSD that I don't understand well enough > right now. One of them is software RAID striping and it sounds like ccd > does this? Disk striping, yes. See: metropolis# df -k Filesystem 1K-blocks Used Avail Capacity Mounted on /dev/sd0a 140862 16094 113500 12% / /dev/sd0s1e 302222 155148 122898 56% /usr /dev/sd0s1f 271886 150922 99214 60% /usr/src /dev/sd10s1e 704559 339752 308443 52% /var /dev/ccd0e 1500399 246615 1133753 18% /usr/local /dev/ccd1e 1971087 162356 1651045 9% /news /dev/ccd2e 1971087 689629 1123772 38% /news/.0 /dev/ccd3e 1971087 291799 1521602 16% /news/.1 /dev/ccd4e 1971087 262458 1550943 14% /news/.2 /dev/ccd5e 1971087 115531 1697870 6% /news/.3 /dev/ccd6e 8075148 2672880 4756257 36% /news/.4 /dev/sd20s1e 1001951 680219 241576 74% /news/.5 procfs 4 4 0 100% /proc amd:493 0 0 0 100% /home /dev/ccd0h 501359 1 461250 0% /export/home/u0 It works, it's great, it's fast, I've seen this system process 11 new articles/second after a downtime, while feeding half a dozen other systems and a slave reader. You will notice the disks are mostly empty. What I really wanted was disks that were just a few hundred megs each, I am not going for a long expire period on a machine that is exclusively a feeder, but there were no fast drives <<< 1GB out on the market anymore, and the 1G drives were _cheap_. > Another one is whether FreeBSD supports MMAP. For active? Yes, but some say not reliably. I see no real difference whether or not I am using it, these days, so I leave it off. > And then there is the whole NNRPD shared active thingy. Works fine. If you have a mongo active file, don't forget to adjust the constants in the patch accordingly. > There have already been a couple of messages that make me think FreeBSD > might be the better choice of OS here. Since running an effective fullfeed > USENET news server is getting harder and harder these days I'm sure that > there are others who would welcome hearing about how it is done. Build it for speed and as close to zero latency as possible. Use more disks instead of less. Stripe lots of FAST 1GB disks - like the new Hawk 31055's - instead of going with larger drives. 2 9ms 1G disks are ALWAYS faster than 1 8ms 2G disk, and the price is similar! Go with more SCSI busses. NCR controllers are $60 apiece. Get three, and a 10/100 PCI Ethernet controller, and you're still only putting out about $350 for your I/O controllers. Use a large stripe size. I use 1 cylinder group. You are not striping for bandwidth. You are striping for CONCURRENCY. You _want_ one mechanism to be able to handle an _entire_ file access on its own. You can see that the machine above was just built for speed. All disks are striped across controllers, they are FAST Hawk drives, etc. etc. Don't compromise on RAM. Stuff it. My feeds box has 128MB RAM. The readers have 256MB (we had some fun with that though). And it was relatively cheap to build, compared to your average Sun system. ... Joe ------------------------------------------------------------------------------- Joe Greco - Systems Administrator jgreco@ns.sol.net Solaria Public Access UNIX - Milwaukee, WI 414/546-7968
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