Date: Tue, 24 Oct 2006 02:21:06 +0200 From: "Ronald Klop" <ronald-freebsd8@klop.yi.org> To: "Chuck Swiger" <cswiger@mac.com>, "Mike Jakubik" <mikej@rogers.com> Cc: stable@freebsd.org Subject: Re: Running large DB's on FreeBSD Message-ID: <op.thwglg1v8527sy@guido.klop.ws> In-Reply-To: <5B0599EE-17BE-44E1-8CEC-587FFF1D79C4@mac.com> References: <453D49D2.1010705@rogers.com> <3861E2E8-4232-4C46-8D0A-1B6079BCA07D@mac.com> <453D53ED.5050403@rogers.com> <5B0599EE-17BE-44E1-8CEC-587FFF1D79C4@mac.com>
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On Tue, 24 Oct 2006 02:00:22 +0200, Chuck Swiger <cswiger@mac.com> wrote: > On Oct 23, 2006, at 4:44 PM, Mike Jakubik wrote: >>> Moderately...it kinda depends on the budget available. I regard >>> Solaris + Oracle as one of the most reliable combinations for moderate >>> to extreme load, for a system that might well be in operation for five >>> to ten years. If I was going to do FreeBSD, I might look into >>> Postgres instead of MySQL; well, I might look into something else than >>> MySQL under many circumstances. I've gotten some pretty good use out >>> of OpenBase, for another choice. >> >> I believe the front-end application is MySQL dependent, but what is so >> much better about PostgreSQL? I understand that it has some more >> advanced features, but if they are not used, then what is the >> advantage? (I really like the InnooDB storage in MySQL) > > I'm not sure whether avoiding deadlocks and using row-level locking by > default qualifies as "advanced features", but unless you use InnoDB with > MySQL, you don't get that from MySQL. Postgres has been around for a > lot longer, and isn't as volatile as MySQL seems to be; also, it avoids > some of the needless timer overhead that MySQL seems to enjoy, and the > less-accurate-but-much-quicker gettimeofday() under Linux helps MySQL on > that platform versus FreeBSD. > >>> As for the disk configuration, using RAID-5 is one of the worst >>> possible choices for a database; using multiple RAID-1 mirrors or a >>> RAID-10 config would probably do a lot better in terms of performance >>> and reliability. >> >> Is RAID5 really that bad when a lot of fast disks are used and the >> controller has a decent cache with a BBWC? Thanks for the feedback guys. > > Yes, RAID-5 really can be that bad, unless your database is read-only or > read-mostly. Lots of small writes will perform badly under RAID-5, even > with a battery-backed write-cache in write-back mode... Example: writing 1 bit on 1 disk needs to read some info from all disks to recalculate the parity. So this doesn't scale very well. -- Ronald Klop Amsterdam, The Netherlands
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