From owner-freebsd-hackers Wed Oct 2 04:15:06 1996 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.5/8.7.3) id EAA29279 for hackers-outgoing; Wed, 2 Oct 1996 04:15:06 -0700 (PDT) Received: from chacal.noc.demon.net (chacal.noc.demon.net [193.195.224.116]) by freefall.freebsd.org (8.7.5/8.7.3) with SMTP id EAA29269 for ; Wed, 2 Oct 1996 04:15:02 -0700 (PDT) Received: by chacal.noc.demon.net with local (Exim 0.42 #3) id E0v8PF4-0005Nt-00; Wed, 2 Oct 1996 12:13:30 +0100 From: jrg@demon.net (James R Grinter) Date: Wed, 2 Oct 1996 12:13:29 +0000 In-Reply-To: <199610020544.PAA18948@eterna.com.au> "Re: VPS mailing list, BSD interest?" (Oct 2, 8:09) X-Subliminal: vitae summa brevis spem nos, vetat incohare longam Organization: Demon Internet, Network Operations Centre X-Mailer: Mail User's Shell (7.2.5 10/14/92) To: matthew green Subject: Re: VPS mailing list, BSD interest? Cc: hackers@freebsd.org, tech-kern@netbsd.org Message-Id: Sender: owner-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk [large cc lists trimmed, i think everyone must be on one of the two lists] On Wed 2 Oct, 1996, matthew green wrote: >i also like the model of ODS (as under solaris 2): > - a metadevice acts like a normal disk partition > - a metadevice can be composed of any number of real partitions > or metadevices, either concatenated or striped, or mirrored. I (having been playing with IRIX 6.2 a lot recently) like IRIX's XFS/XLV setup. It's pretty similar to Sun's ODS/SDS, but you don't have to change md.conf files and reinit the metadevice when you move disks around controllers and change their ids. At boot time, an 'assemble' operation checks all disks on the system, and finds details of which logical volume they belong to, if any. (Someone's already said that they think it useful to be able to easily reconfigure your disks, and I concur - when you're dealing with large numbers of disks and large numbers of controllers you really don't want to have to be writing down numbers on pieces of paper.) Each logical volume has a name which is used when referring to the logical volume device (/dev/{r,}dsk/xlv/volumename), and consists of log, data, and real-time data sub-volumes. Each sub-volume consists of a number of volume elements (each being a disk partition), which can be concatenated or striped together. A sub-volume can contain up to 4 plexes (SGI's term for mirrors), each being up to 128 volume elements. Of course, SGI have the advantage of not having tried to build the system around UFS/FFS, so you grow the filesystem whilst it is mounted (the instructions specifically say you *must* mount before growing!), and it's far better in crash situations. for some pointers to XFS/XLV concepts. -- jrg.