From owner-freebsd-questions Thu May 14 19:32:37 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id TAA12191 for freebsd-questions-outgoing; Thu, 14 May 1998 19:32:37 -0700 (PDT) (envelope-from owner-freebsd-questions@FreeBSD.ORG) Received: from freebie.lemis.com (freebie.lemis.com [139.130.136.133]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id TAA12132 for ; Thu, 14 May 1998 19:32:21 -0700 (PDT) (envelope-from grog@lemis.com) Received: (from grog@localhost) by freebie.lemis.com (8.8.8/8.8.7) id MAA00731; Fri, 15 May 1998 12:02:19 +0930 (CST) (envelope-from grog) Message-ID: <19980515120219.K305@freebie.lemis.com> Date: Fri, 15 May 1998 12:02:19 +0930 From: Greg Lehey To: "Donald E. Lyon, Jr. Ph.D." , freebsd-questions@FreeBSD.ORG Subject: Vinum (was: RAID) References: <000301bd7f4e$a5579900$01c7c7c7@msoft> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.91.1i In-Reply-To: <000301bd7f4e$a5579900$01c7c7c7@msoft>; from Donald E. Lyon, Jr. Ph.D. on Thu, May 14, 1998 at 08:40:39AM -0700 WWW-Home-Page: http://www.lemis.com/~grog Organization: LEMIS, PO Box 460, Echunga SA 5153, Australia Phone: +61-8-8388-8286 Fax: +61-8-8388-8725 Mobile: +61-41-739-7062 Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Thu, 14 May 1998 at 8:40:39 -0700, Donald E. Lyon, Jr. Ph.D. wrote: > >> From: Greg Lehey [mailto:grog@lemis.com] >> Sent: Monday, May 11, 1998 4:53 PM >> >> On Mon, 11 May 1998 at 14:56:20 -0700, Doug White wrote: >>> On Mon, 11 May 1998, Donald E. Lyon, Jr. Ph.D. wrote: >>> >>>> 1. Does FreeBSD have something like SCO's Virtual Disk Manager (RAID)? >>> >>> Although I'm not familiar with that product directly, we do have ccd, >>> which is disk striping. That may be supplanted by vinum in the future, >>> which is much more flexible. >> >> I'm the author of vinum. I don't know about the Virtual Disk Manager, >> but it could be something similar. Could you describe it, please? > > The SCO Virtual Disk Manager is an add-on, layered product that enhances the > ability of SCO OpenServer Release 5 to provide flexible configurations of > high reliability, high performance data storage. Thanks. This looks pretty much the same thing as vinum. I've just released the first alpha test version, but I don't recommend it to anybody who isn't prepared for a lot of work in getting it into shape. Greg > Virtual disks are used to organize data in multi-disk systems. Areas from > several discrete hard disks can be assigned to a virtual disk, which is > accessible as if it were a single physical disk by applications running on > the system. > > Virtual disks can support partitions larger than a single disk's physical > extent. In addition, virtual disks can be organized so that I/O requests are > written to an array of disk drives in parallel. This can be used to mirror > data (providing increased security against hardware failures), or to stripe > data across multiple disks (improving performance). > > There are several virtual disk types: most are implemented as RAID > (redundant array of inexpensive disks) configurations. In this release, RAID > configurations 0, 1, 4, 5, 10 and 53 are supported. > > Disk "pieces" can be assigned to virtual disks as needed. Some virtual disk > types can use this facility in the event of a hardware failure. A disk piece > is brought online from a spare disk drive kept on hot standby, and the lost > data is regenerated from the parity information and data stored on the other > drives in the array. This permits an array to keep working at near-optimal > performance despite isolated hardware failures. > > Virtual disks can be administered without taking the system offline, > including online reconfiguration, online restore, and online data > verification. This capability reduces disk downtime due to storage system > reconfiguration and performance tuning. > > Virtual disks are used to manage data in a more flexible way on systems with > multiple hard disks. They are particularly useful for improving the > performance of large applications, such as databases, by distributing the > data across multiple disks and speeding up disk I/O. > > Units of virtual disk space look like real disk partitions to programs > running on the system, but their characteristics can be changed dynamically > using the Virtual Disk Manager. > > The Virtual Disk Manager adds an additional level of software control to the > allocation of data storage. Normally, when applications request some data > from the filesystem, the kernel uses the filesystem to discover the disk > blocks where the data is stored and returns the data directly. When a > virtual disk is in use, the system reads and writes to a virtual disk > driver, which in turn manages the physical allocation of data across several > disks. > > This has a number of advantages. A virtual disk can be assembled from a > collection of small disks, or pieces of disks, so that rather than providing > a set of small partitions they can be used to provide a single large > contiguous disk space. Data can be duplicated (``mirrored'') across drives, > so that if one drive succumbs to a hardware failure, the system can continue > to operate without interruption: by using a technique called ``striping'', > data can be read from and written to disks in parallel, significantly > improving I/O performance. > > Etc... > > This was copied from www.sco.com, Openserver, Virtual Disk Manager pages. -- See complete headers for address and phone numbers finger grog@lemis.com for PGP public key To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message