Re: software vs hw hard on linux

My personal experience with RAID cards is that you have to spend money to get good performance. You need battery backed cache because RAID 5 only works well with write to cache turned on, and you need a good size cache too. If you don't have it, RAID 5 performance will suck big time. If you need speed, RAID 10 seems to be the only way to go, but of course that means you are gonna spend $$s on drives and chasis. I wish someone would start a website like storagereview.com for RAID cards because I have had _vastly_ differing experience with different cards. We currently have a compaq ML370 with a Compaq Smart Array 5300, and quite frankly it sucks (8MB/sec write). I get better performance numbers off my new Tyan Thunder s2469UGN board with a single U320 10k RPM drive (50MB/sec) than we get off our RAID 5 array including seeks/sec. Definately shop around, and hopefully some other folks can give some suggestions of a good RAID card, and a good config.

Alex Turner

P.S. If there is movement for a RAID review site, I would be willing to start one, I'm pretty dissapointed at the lack of resources out there for this.

On Fri, Sep 12, 2003 at 10:34:26AM -0400, Jeff wrote:
> Due to various third party issues, and the fact PG rules, we're planning
> on migrating our deplorable informix db to PG. It is a rather large DB
> with a rather high amount of activity (mostly updates). So I'm going to
> be aquiring a dual (or quad if they'll give me money) box. (In my testing
> my glorious P2 with a 2 spindle raid0 is able to handle it fairly well)
>
> What I'm wondering about is what folks experience with software raid vs
> hardware raid on linux is. A friend of mine ran a set of benchmarks at
> work and found sw raid was running obscenely faster than the mylex and
> (some other brand that isn't 3ware) raids..
>
> On the pro-hw side you have ones with battery backed cache, chacnes are
> they are less likely to fail..
>
> On the pro-sw side you have lots of speed and less cost (unfortunately,
> there is a pathetic budget so spending $15k on a raid card is out of the
> question really).
>
> any thoughts?
>
> --
> Jeff Trout <jeff(at)jefftrout(dot)com>
> http://www.jefftrout.com/
> http://www.stuarthamm.net/
>
>
>
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