Date: Mon, 6 Dec 1999 18:11:46 -0800 (PST) From: <keith@cydonia.net> To: David Wolfskill <dhw@whistle.com> Cc: freebsd-newbies@FreeBSD.ORG Subject: Re: Tape Backup Message-ID: <Pine.LNX.4.04.9912061811330.21806-100000@mail.cydonia.net> In-Reply-To: <199912070112.RAA45807@pau-amma.whistle.com>
next in thread | previous in thread | raw e-mail | index | archive | help
Great info.. Thanks a ton.. Keith On Mon, 6 Dec 1999, David Wolfskill wrote: > >Date: Mon, 6 Dec 1999 13:34:14 -0800 (PST) > >From: <keith@cydonia.net> > > >In need of some understanding/help. When installing a tape backup system. > >Is it important to have compatability? > > Hmmm.... > > >I mean, does the system see it as a simple IDE/SCSI device > >and not realy care what brand/model of tape backup system is?? > > The tape drive would usually be a "simple IDE/SCSI device" -- well, it > has been in all the systems I've used (over the last 30 years). > > >Does the OS have to make a file system on the tape or is that a function > >of the tape drive itself? > > Generally, tape devices do not contain "file systems," since that > implies a degree of random access that a tape would require far too much > latency to support. Further, tape drives are usually designed in such a > way that once data has been written to the tape in a given place, you > can't read data from "beyond" that point in the tape. (DECtapes are a > little different, I understand....) > > Basically, a tape device usually acts as a device to which a stream of > byte may be written or from which a stream of byte may be read. Put > another way, it's a sequential (vs. random-access) device. > > >I'm going to be useing dump in FreeBSD > >to do the backups > > "dump" is a program that reads a filesystem and generates a "stream of > bytes"; its output can be assigned to "standard output" (and thus > suitable for the input to a pipeline, for example, as well as writing to > a sequential device, such as tape). > > >and don't realy have a good understanding of how tape > >devices work in FreeBSD. > > Pretty much as they do in most UNIX systems -- you can write sequential > data to them and reasd sequential data from them. There are conventions > for writing "file marks" when a file is closed after having been opened > for writing; that's how multiple files can be written to a single tape. > > >It's my understanding that there realy doesn't > >need to be any real compatability becouse FreeBSD will just comunicate to > >the device and the device takes care of the actual writing it in the > >proper format on the tape no real need for a "driver" for a specific tape > >device.. Thanks for any help. > > Not sure how you're intending to use the word "compatability" up there. > > The driver usually just treats the tape drive as a generic device, > though -- as opposed, for example, to the way Ethernet NICs are > handled, or SCSI host adapters. > > Cheers, > david > -- > David Wolfskill dhw@whistle.com UNIX System Administrator > voice: (650) 577-7158 pager: (888) 347-0197 FAX: (650) 372-5915 > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-newbies" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?Pine.LNX.4.04.9912061811330.21806-100000>