Date: Sun, 30 Jan 2000 21:37:06 -0800 (PST) From: Tom <tom@sdf.com> To: Greg Lehey <grog@lemis.com> Cc: Marc Tardif <admin@wtbwts.com>, freebsd-scsi@FreeBSD.ORG Subject: Re: hardware vs software stripping Message-ID: <Pine.BSF.4.05.10001302130260.5637-100000@misery.sdf.com> In-Reply-To: <20000131155356.B68925@freebie.lemis.com>
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> > 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. 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.
...
> > 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.
> Greg
> --
> Finger grog@lemis.com for PGP public key
> See complete headers for address and phone numbers
>
>
Tom
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