Date: Thu, 6 Sep 2001 15:28:41 +0930 From: Greg Lehey <grog@FreeBSD.org> To: "Chad R. Larson" <chad@DCFinc.com> Cc: Jason DiCioccio <geniusj@bluenugget.net>, FreeBSD-Stable <stable@FreeBSD.ORG> Subject: Re: CCD vs VINUM [was Re: RAID5] Message-ID: <20010906152841.K24413@wantadilla.lemis.com> In-Reply-To: <20010905142751.B6345@freeway.dcfinc.com>; from chad@DCFinc.com on Wed, Sep 05, 2001 at 02:27:51PM -0700 References: <20010903142145.K10812-100000@topperwein.dyndns.org> <200109041749.KAA12474@mina.soco.agilent.com> <20010905014103.A70986@bluenugget.net> <20010905142751.B6345@freeway.dcfinc.com>
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On Wednesday, 5 September 2001 at 14:27:51 -0700, Chad R. Larson wrote: > On Wed, Sep 05, 2001 at 01:41:03AM -0700, Jason DiCioccio wrote: >> vinum, IMHO, has the BEST manpage I've ever seen out of an open source >> product. >> >> It has a ton of examples and explains things very well although it's >> quite lengthy. Therefore i'm not sure what the issue was with setting >> up the mirror. > > Is there a pointer somewhere to a comparison between ccd and vinum? Not that I know of. As far as I can tell: 1. CCD only provides concatenation, striping and mirroring. I don't expect it to perform significantly differently from Vinum in this area. 2. You can argue the point, but I find Vinum configuration more understandable. 3. CCD doesn't save the configuration information on the disk. Lose the config file and your disks are toast. With Vinum, on the other hand, you can remove the drives, change the IDs, replace them and restart with no further problems. 4. Vinum notes the state of each component in the saved configuration. If one component of a mirror goes down and the other continues to be updated, it will still know the fact after a reboot, thus ensuring data integrity. CCD doesn't save the state anywhere. 5. (I'm not sure if this is still the case, but I haven't heard of any change). If half a CCD mirror goes down, you need to take the ccd down and reconfigure, maybe reboot, before you can use the other half. With Vinum, you can carry on using the volume, and if the hardware permits it, you can rebuild online. 6. Vinum has a whole lot more features, like dynamic reconfiguration, multiple mirrors, RAID-5 (and RAID-4, because somebody insisted; don't use it). Greg -- See complete headers for address and phone numbers To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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