Date: Fri, 9 Jul 1999 11:26:45 +0930 From: Greg Lehey <grog@lemis.com> To: The Clark Family <Clark@open.org> Cc: mavery@mail.otherwhen.com, jsd@gamespot.com, freebsd-questions@FreeBSD.ORG Subject: Re: HP T4000s Tape Drive problems Message-ID: <19990709112645.Q6035@freebie.lemis.com> In-Reply-To: <199907082224.PAA27606@opengovt.open.org>; from The Clark Family on Thu, Jul 08, 1999 at 03:53:08PM -0700 References: <199907082054.NAA03455@hudsucker.gamespot.com> <199907080218.VAA14937@hostigos.otherwhen.com> <199907082142.QAA16185@hostigos.otherwhen.com> <199907082224.PAA27606@opengovt.open.org>
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On Thursday, 8 July 1999 at 15:53:08 -0700, The Clark Family wrote: > At 04:39 PM 7/8/99 -0500, Mike Avery wrote: >> On 8 Jul 99, at 13:54, Jon Drukman wrote: >> >>>> I've resolved backup problems in several shops by just ditching the >>>> Travan drives. These weren't the cheapos, they were the "professional" >>>> NS-8 and NS-20 series drives. >> >>> Based on what you and a few others have said about general Travan >>> crappiness, I will follow your advice and put this thing back in >>> the cupboard from whence it came, and instead play around with >>> this Exabyte 8500 I found. >> >>> On a somewhat related note, does anybody have any strong preferences >>> between DAT/DLT/Exabyte? I'm interested in all experiences, good or >>> bad... Let me know. >> >> I have an ExaByte 8505XL, and I'm very happy with it, overall. It's >> fairly quick, good capacity, and I can usually use commercial (video) >> 8mm tapes in it and save money. It's big drawback is that it's seek >> time is a LOT longer than that of a DAT or DLT. I don't know that >> I'd buy another one if this one died, but I am happy with it, and I do >> trust it. >> >> I've used more than a few DAT drives. I like Archive and Seagate a >> lot. I can live with HP. The HP's seem to flake out and need to be >> overhauled. Things might have gotten better since I stopped using >> them... I wouldn't know about that. I've had good luck with, and >> heard good reports on, the Seagate 12/24 gig DAT drive.... the >> Scorpion I think. >> >> As to DLT drives, I've used 'em, but not often. A bit rich for my >> blood. Those who use 'em seem to love 'em. Very fast. However, >> be aware that there are only two drive manufacturers now. >> Quantum and Tandberg. If it doesn't say Tandberg, it's a >> Quantum. (As far as I know, Tandberg isn't OEM'ing yet.) >> Quantum's are good drives, so the point isn't "avoid quantum", it's >> "don't pay more than you have to, they're all the same damn drive". >> >> Another consideration.... the 4000 series is rated at about 1.5mbps. >> The 7000 at about 5... if memory serves. Many servers (your >> hardware, backup software, server load, and OS will cause the >> mileage to vary) can't deliver a byte stream fast enough to keep a >> 7000 series drive in streaming mode, so it goes into start-stop mode. >> This destroys the throughput.... slower than a 4000 series drive in >> practice. So, unless you are VERY sure you have the bandwidth (and >> more than one person has been surprised here), stay with a 4000 >> series drive. Or two 4000 series drives for more capacity. > > The HP stuff is 4mil isn't it? If so, DAT is 8mil right? So HP isn't DAT > its 4mil. DAT is 4mm digital audio. Video 8 is 8mm analogue video. HP is DDS, which uses the same form factor cartridges as DAT, but they are *not* DAT. Most HP drives will reject DAT tapes unless you override a configuration option. Exabyte uses the same form factor as Video 8, but again, the cartridges are different. You're asking for trouble using Video 8 cartridges in Exabytes: they'll work, sort of, but you'll get a much higher soft error rate than with real data grade cartridges. And there's really not much difference in price if you know where to shop; I used to be able to get data cartridges cheaper than Video 8. They worked fine in my video camera :-) > My theory is, if your servers can't keep up a stream of data > sufficient to keep a DLT7000 streaming, then you need to rethink how > you build servers. > > If you go with multiple 4000s, get three so you can stripe across them. > (grin) I have a DLT4000. I can't keep it streaming, but it still goes faster than my Exabyte and DDS drives. If you have any ideas on how to keep it streaming, I'd be open to them. Greg -- When replying to this message, please copy the original recipients. For more information, see http://www.lemis.com/questions.html See complete headers for address, home page 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
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