Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!samsung!uunet!mcsun!ukc!axion!delluk!tim From: tim@dell.co.uk (Tim Wright) Newsgroups: comp.periphs.scsi Subject: Re: RAID in hardware? Message-ID: Date: 26 Feb 91 15:25:01 GMT References: <540@zds-ux.UUCP> <3229@legs.UUCP> Sender: usenet@delluk.uucp (Usenet posting login) Organization: Dell Computer Corp., Bracknell, UK Lines: 32 In <3229@legs.UUCP> cgn@ast.COM (Chris Nieves) writes: >In article <540@zds-ux.UUCP>, bjstaff@zds-ux.UUCP (Brad Staff) writes: >> Is anybody working on implementing RAID algorithms in hardware? I'd >> envision something like a SCSI-2 target controller, which controls N >> IDE/ESDI/SCSI/? disks. Or maybe something completely different? >> -- >It doesn't make a whole lot of sense to have your cpu reading data, >XORing it, and writing the parity to memory, BEFORE you even start >the disk request. It seems best to have a SCSI (IDE?) controller >handling all of the parity generation and data correction. This way >the OS would need to have very little knowledge that there is anything >special out there other than a real big, fast disk. Sorry, I missed the original posting (it may be in the pipeline - the UK has been cut off from the US for a few days). Anyway, this is EXACTLY what the Dell Drive Array does. It's an EISA card which supports up to 10 IDE drives (spindle-sync'd or not), and these can be configured as N logical drives of up to five physical drives each, with or without data-guarding (XOR of the data on the redundant drive). To UNIX, it looks like an Adaptec SCSI controller. So to answer the question(s), it has been implemented in hardware and it does just look like a big, fast hard disk. Incidentally the hardware in question is an Intel i960 - you need something fairly powerful ! Tim -- Tim Wright, Dell Computer Corp., Bracknell | Domain: tim@dell.co.uk Berkshire, UK, RG12 1RW. Tel: +44-344-860456 | Uucp: ...!ukc!delluk!tim Nobody ever said I was charming before. They said, "Rimmer, you're a total git" - Red Dwarf, "Camille".