Date: Sun, 16 Sep 2001 21:43:40 +0200 From: Bernd Walter <ticso@mail.cicely.de> To: Bob Van Valzah <Bob@BGPBook.Com> Cc: Murray Stokely <murray@FreeBSD.ORG>, Greg Lehey <grog@lemis.com>, doc@FreeBSD.ORG Subject: Re: Reviewers for Bootstrapping Vinum Doc Message-ID: <20010916214340.A21757@cicely20.cicely.de> In-Reply-To: <3BA3BDD6.8060401@BGPBook.Com>; from Bob@BGPBook.Com on Sat, Sep 15, 2001 at 03:45:10PM -0500 References: <3BA01768.2000902@BGPBook.Com> <20010912205708.L9233@windriver.com> <20010913152014.A783@canberra.worldwide.lemis.com> <3BA1FFEE.7000305@BGPBook.Com> <20010914140434.E9233@windriver.com> <3BA3BDD6.8060401@BGPBook.Com>
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On Sat, Sep 15, 2001 at 03:45:10PM -0500, Bob Van Valzah wrote: > Ok, I have a document ready for your review. There's still a lot of > "tweaking" I'd do given the luxury of time, but I wanted to get you and > Greg something fast. It's about 25 pages. See http://www.BGPBook.Com/vinum/ I've found the following points in Table 1. The MTBF for a RAID1 is increased not halfed. In fact the MTBF for striped and concatenated is also not halfed. The MTBF for a 2 disk RAID0 is somewhere between 1/2 and 1. And for a 2 disk RAID1 it is somwhere between 1 and 2. It depends on how strong the variations of real failures from the MTBF is. Say we have 2 disks with an MTBF of 5 years. Asume the unlikely case that we have no varianz on the 5 years, which means a RAID0 with these disks will also have an MTBF of 5 year. To calculate both thing statisticaly right you need to know the standart divergence of the MTBF. Well vendors only name the MTBF so you should at least mark it as a worst case. I did not read it completely yet so this is not a comment on the complete document. -- B.Walter COSMO-Project http://www.cosmo-project.de ticso@cicely.de Usergroup info@cosmo-project.de To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-doc" in the body of the message
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