Date: Wed, 3 Feb 1999 09:56:14 -0800 From: Don Lewis <Don.Lewis@tsc.tdk.com> To: Joerg Wunsch <joerg_wunsch@uriah.heep.sax.de>, freebsd-scsi@FreeBSD.ORG Subject: Re: SCSI Tape Drives... Message-ID: <199902031756.JAA15738@salsa.gv.tsc.tdk.com> In-Reply-To: J Wunsch <j@uriah.heep.sax.de> "Re: SCSI Tape Drives..." (Feb 3, 7:20am)
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On Feb 3, 7:20am, J Wunsch wrote: } Subject: Re: SCSI Tape Drives... } As Don Lewis wrote: } } > Our old Exabytes didn't last all that long, either, as I recall. } } Neither did ours, btw. Most of them fell into the habit of never } wanting to give you your tape back some day. And when you open them up, you'll find tape wrapped around their innards. } > When used for daily backups, my experience is that QIC-150 drives } > don't last too long, and that's backup up a lot less data that I } > have been archiving with DAT. } } Hmm, what kind of QIC-150 drives? The old Wangteks are built very } cheaply. Whatever Sun was shipping, usually Wangtek and Archive. It looks like we've got two Archive QIC-150's connected to our Suns now, one of which is original, and one is a replacement. They haven't seen much use in years. } OTOH, i didn't have any bad experience (so far) with } Tandberg QIC drives, and there are some three drives (TDC 4222, 2.5 GB } + compression) around me doing nightly backups for years now. QIC } media have a good lifetime (unlike DAT), and it's not a problem to use } the very same tape every night for a year or more. (Two of the three } drives are used in an operatorless environment where it's simply } impossible to change the medium on something like a daily or weekly } basis. So far, in one of those machines, the backup has already saved } our butt for two dead disks.) HP claims that DAT tapes are good for some outrageously large number of passes. I don't really believe them, so I replace tapes a lot more often than they say I should need to. Our Amanda backups are run five days per week, with 25 tapes in the set, so each tape is used once every five weeks. I replace the tapes every two years, which means that the tapes are used 20 times, plus a few times for restores. The drives wear out before the tapes :-( I think if HP's information about lifetime of the tapes is true, that we could repeatedly reuse the same tape every day and it would still have some life left at the time we see the drive fail. } > I've also had problems with media } > interchange between QIC drives. } } Sounds like you've got a broken or worn-out drive. I've never } experienced this, and my drive can still read any QIC cartridge } around, with some of them being almost ten years old now. The QIC-150 drive that was replaced couldn't read some tapes. When it died, it's replacement also can't read some tapes, but the QIC-150 drive on one of the other machines can. } > We're switching over to DLT for backups here at work, but the drive } > and media are really too pricey for home use, and I don't need that } > much capacity. } } Just to clarify: i think about the same, and we also use DLT at work. } } > + Media cost } > } > I'd guess that 8mm and DAT come in first and second here. } } Hmm, not if you consider the short lifetime of a DAT cassette. OTOH, } i've got a pile of QIC-150 cartridges on a shelf stemming from } software vendors like you mentioned, so they are for free, and they } still serve well enough for small quantities of data. The TDC 4222 is } probably about 5 years old now, and so far i haven't needed more than } 10 of the higher-density (and more expensive) cartridges. Most of the QIC tapes I've got are pretty old now, and judging by my old audio tapes which are shedding oxide, I don't really trust them that much. There are also quite a few QIC-24 tapes mixed in, which are pretty useless. --- Truck To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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