Date: Sun, 25 Nov 2001 23:26:15 -0800 From: "Ted Mittelstaedt" <tedm@toybox.placo.com> To: "Anthony Atkielski" <anthony@freebie.atkielski.com>, "Christopher Farley" <chris@northernbrewer.com>, "Noor Dawod" <noor@comrax.com> Cc: <freebsd-questions@FreeBSD.ORG> Subject: RE: SCSI tape back that works under FreeBSD Message-ID: <001801c1764b$a22764c0$1401a8c0@tedm.placo.com> In-Reply-To: <000e01c1760a$0d14ebf0$0a00000a@atkielski.com>
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>-----Original Message----- >From: owner-freebsd-questions@FreeBSD.ORG >[mailto:owner-freebsd-questions@FreeBSD.ORG]On Behalf Of Anthony >Atkielski >Sent: Sunday, November 25, 2001 3:37 PM >To: Christopher Farley; Noor Dawod >Cc: freebsd-questions@FreeBSD.ORG >Subject: Re: SCSI tape back that works under FreeBSD > > >I have always had excellent luck with Hewlett-Packard DAT drives. As long as >you don't reuse tapes beyond their useful lives (whatever number of >passes the >manufacturer recommends, usually several hundred at least), and keep >the drive >clean per HP's instructions, it is very reliable. > I have used Exabyte, HP, Sony, Archive, and a few other 4 and 8mm helical scan DAT drives over the past 10 years at various companies I've worked at. HP DAT drives on average are no better or worse than any other heli-scan DAT drive. DAT drives are fine for light-duty backup tasks, such as a full backup once a month and an incremental once a week (or whenever the network admin feels like it) However ALL heli-scan DAT drives WILL eventually get out of alignment. This is exactly what happens to a VCR. With VCR's though, they are so cheap you just toss them in the trash and buy another. DAT drives are something else. If you have only a single DAT drive in your setup you likely will not notice this problem until the drive is very, very, very out of alignment. But if you have multiple DAT drives you will notice it rather quickly espically if each drive comes from a different manufacturer, because each will go out of alignment differently. The result is that after a year or so of _heavy_ use (and I'm talking 2/3 to full usage of a tape cartridge every night) each tape drive will not be able to read tapes from the other drive in it. Each drive will of course continue to be able to read it's OWN tapes. The problem will continue to progress until eventually the drive claims that every tape you put in it - including ones that are brand new - have a large number of bad blocks on them. Heli-scan technology was a good thing when it came out, but today there's DLT which is much better in terms of reliability in a production environment. If you must use DAT, then keep an eye on the number of bad blocks that the drive reports were found during a backup operation. When that figure starts to rise then get the tape drive realigned before you start tossing tapes. Ted Mittelstaedt tedm@toybox.placo.com Author of: The FreeBSD Corporate Networker's Guide Book website: http://www.freebsd-corp-net-guide.com >----- Original Message ----- >From: "Christopher Farley" <chris@northernbrewer.com> >To: "Noor Dawod" <noor@comrax.com> >Cc: <freebsd-questions@FreeBSD.ORG> >Sent: Monday, November 19, 2001 22:13 >Subject: Re: SCSI tape back that works under FreeBSD > > >> Noor Dawod (noor@comrax.com) wrote: >> >> > Hi, >> > >> > I want to buy a SCSI tape backup (DAT) for our server. Can >anyone recommend >> > a good one? fast and reliable that works under FreeBSD. >> >> I think just about any SCSI tape drive will work under FreeBSD. >> I've used a couple different types of SCSI drives (DAT, DLT) under >> FreeBSD and found it to be utterly painless to set them up. >> >> > While we're at it, how do you back up to one of these tape drives? >> >> In believe FreeBSD recognizes a SCSI tape drive as /dev/nrsa0. >> >> Most of the tape backup programs (certainly dump, maybe tar and cpio) >> use the correct device by default. >> >> The mt command (man mt) is also useful for manipulating the tape drive >> (checking the status, positioning the tape to the right file, rewinding >> or retensioning the tape, etc). >> >> -- >> Christopher Farley >> www.northernbrewer.com >> >> To Unsubscribe: send mail to majordomo@FreeBSD.org >> with "unsubscribe freebsd-questions" in the body of the message >> > > >To Unsubscribe: send mail to majordomo@FreeBSD.org >with "unsubscribe freebsd-questions" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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