Date: Mon, 31 Jan 2000 16:27:31 +1030 From: Greg Lehey <grog@lemis.com> To: Tom <tom@sdf.com> Cc: Marc Tardif <admin@wtbwts.com>, freebsd-scsi@FreeBSD.ORG Subject: Re: hardware vs software stripping Message-ID: <20000131162728.C68925@freebie.lemis.com> In-Reply-To: <Pine.BSF.4.05.10001302130260.5637-100000@misery.sdf.com> References: <20000131155356.B68925@freebie.lemis.com> <Pine.BSF.4.05.10001302130260.5637-100000@misery.sdf.com>
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On Sunday, 30 January 2000 at 21:37:06 -0800, Tom wrote: > >>> Second, a DPT can't do RAID 5 + 0. It does the RAID 5 in >>> hardware. The RAID 5 you'll have to do in software. > RAID 0 >> >> Hmm. There's obviously a typo here, but I'm not sure how to correct >> it. I don't know the DPT implementation, but in Vinum RAID-5 implies >> striping. I'd be interested in hearing how DPT does it. > > RAID 5 on the DPT. RAID 0 in software. You misunderstand. RAID-5 in Vinum is implemented as a variant of RAID-0. Check http://www.lemis.com/vinum.html for details. > Create two or more RAID 5 volumes on the DPT, then strip all DPT > volumes into one big software volume using ccd (a lot of this > predates vinum). The RAID 0 can help insuluate you from the > generally crummy write performance of RAID 5. Not much. >>> An Infortrend (see below) can do a transparent copy-and-replace array >>> expansion. This however just leaves you with a bigger virtual disk. >>> FreeBSD has no way to grow a filesystem transparently. You can disklabel >>> the addtional space and make a new filesystem though. >> >> In a similar way, you can increase the size of a concatenated Vinum >> plex, or add another, larger plex to a volume. Both would increase >> the size of a volume. Some people also have tools for increasing the >> size of a ufs file system, but they still need work. > > These tools are also strictly off-line too. Solaris' growfs is very > disapointing in that all process that write just block until growfs is > completed. Depending on your application, that may be unacceptable. I can understand the problem. I don't think we'll get any better than that either. Greg -- Finger grog@lemis.com for PGP public key See complete headers for address and phone numbers To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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