Date: Fri, 05 Nov 1999 00:26:14 +0100 From: Mattias Pantzare <pantzer@ludd.luth.se> To: Greg Lehey <grog@lemis.com> Cc: freebsd-fs@FreeBSD.ORG Subject: Re: feature list journalled fs Message-ID: <199911042326.AAA02859@zed.ludd.luth.se> In-Reply-To: Message from Greg Lehey <grog@mojave.sitaranetworks.com> of "Thu, 04 Nov 1999 16:13:17 EST." <19991104161317.49512@mojave.sitaranetworks.com>
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> On Thursday, 4 November 1999 at 1:20:36 +0100, Mattias Pantzare wrote= : > >> I am under the impression that you can only enlarge a vinum volume= if it > >> in a RAID 0 configuration (concatenation). Obviously, it would be ve= ry > >> difficult to enlarge a RAID 1 or RAID 5 configuration as it would re= quire > >> restriping the data across all disks; I'm not familiar with any prod= uct, > >> hardware or software, that can do this. > > > > Solaris DiskSuite almost extends RAID 5 configruations. You can add d= isks to a > > RAID 5 set, but the extra disks will only hold data, no parity. > = > That's normal for RAID-5. Only one disk in any stripe contains the > parity information. Disk, not stripe. > = > > I think that it is a strange mix of RAID 5 and concatenation. All > > data is still parity protected. It might not be as fast as a true > > RAID 5, but it can be very usful. > = > What's the difference? If you have 3 disks and 3 stripes and number sectors from 1 to 6: Disk 1 Disk 2 Disk 3 = 1 2 P = P 3 4 = 5 P 6 = Then add a new disk: Disk 1 Disk 2 Disk 3 New Disk 1 2 P 7 P 3 4 8 5 P 6 9 All you have to do is recalculate the new parity data when you write new = data = if you zero the new disk before using it. Disk accesses will not be spread out as in normal RAID5, but you still ge= t = parity protection. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message
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