Date: Sat, 11 Feb 2006 10:04:09 -0800 From: "Ted Mittelstaedt" <tedm@toybox.placo.com> To: "Derek Ragona" <derek@computinginnovations.com>, "Robert Uzzi" <ruzzi@compedgeracing.com>, <freebsd-questions@freebsd.org> Subject: RE: SATA Raid Message-ID: <LOBBIFDAGNMAMLGJJCKNGEGCFDAA.tedm@toybox.placo.com> In-Reply-To: <6.0.0.22.2.20060211073536.02760858@mail.computinginnovations.com>
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>Most of the cheaper cards just employ software raid, This isn't accurate. All cards, even so-called hardware raid cards, use software in their firmware. "software raid" refers to when the host CPU is doing the raid management, and that isn't what is happening with chips like the promise, highpoint, and intel ich that I posted. Those chips are mirroring/striping only, and do not offer raid 5 so there is no parity calculation going on. Instead, when the driver does a write to the chipset, the chipset duplicates the write between the disks. That is the same principle as the bigger and more powerful hardware raid cards like the compaq/hp intelligent array controller when they are in raid0 The only significant difference between a real raid card like the HP/Compaq intelligent array controller and the cheaper raid chipsets is that you cannot attach the cheaper ata raid chipsets to hot-swap disk drive cages, and pull out one of the hard drives while the server is in operation, replace it, and have the raid controller detect all this and silently rebuild the array without interrupting reads and writes to the host operating system. Instead, if a disk drive dies, you have to shut the server down, replace the drive, and reboot into the BIOS so you can run the utility that rebuilds the array. Ted >-----Original Message----- >From: owner-freebsd-questions@freebsd.org >[mailto:owner-freebsd-questions@freebsd.org]On Behalf Of Derek Ragona >Sent: Saturday, February 11, 2006 5:40 AM >To: Robert Uzzi; freebsd-questions@freebsd.org >Subject: Re: SATA Raid > > >Be wary of any of the cheaper SATA RAID using si chips, there have been >many problems noted you will find searching this list and the >list for current. > >I had a lot of problems with an adaptec card that used one of >those chips. > >Most of the cheaper cards just employ software raid, which is >usually fine >unless you need higher performance. > >Soren is the one to answer on what works well beyond the hardware list. > >Hope this helps. > > -Derek > > >At 09:35 PM 2/10/2006, Robert Uzzi wrote: >>Anyone know of any of the cheaper SATA raid cards that work well under >>FreeBSD. I'd love to go get a 3ware but they are fairly pricey. >> >>_______________________________________________ >>freebsd-questions@freebsd.org mailing list >>http://lists.freebsd.org/mailman/listinfo/freebsd-questions >>To unsubscribe, send any mail to >"freebsd-questions-unsubscribe@freebsd.org" >_______________________________________________ >freebsd-questions@freebsd.org mailing list >http://lists.freebsd.org/mailman/listinfo/freebsd-questions >To unsubscribe, send any mail to >"freebsd-questions-unsubscribe@freebsd.org" > >-- >No virus found in this incoming message. >Checked by AVG Free Edition. >Version: 7.1.375 / Virus Database: 267.15.6/257 - Release Date: >2/10/2006 >
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