Date: Wed, 1 Jul 1998 09:01:55 +0930 From: Greg Lehey <grog@lemis.com> To: Richard Foulk <richard@pegasus.com>, Mike Smith <mike@smith.net.au> Cc: freebsd-hardware@FreeBSD.ORG Subject: Re: Strong opinions, anyone? Message-ID: <19980701090155.V1880@freebie.lemis.com> In-Reply-To: <199806302042.KAA13954@pegasus.com>; from Richard Foulk on Tue, Jun 30, 1998 at 10:42:08AM -1000 References: <mike@smith.net.au> <199806302042.KAA13954@pegasus.com>
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On Tuesday, 30 June 1998 at 10:42:08 -1000, Richard Foulk wrote: >>>>> The Exabyte 8200's are cheap, >>>> >>>> I'd consider them relatively expensive. DDS drives are much cheaper >>>> in Europe. The 8200 is also pretty old now. >>> >>> They are fairly inexpensive some places. >> >> Yes. Buy several, so you have a set of spare parts. > > There are a dozen or more places that repair and refurbish them, mostly > because they were the `only game in town' for so long in the `high > capacity' realm. Right. That doesn't make them reliable, though. >>>> Relatively unreliable. This is old technology (full height stuff). >>>> The more recent drives are much better. >>> >>> Mature technology. Built to be used in data centers, not toys like >>> many of the other pc backup products. >> >> I think "notorious" is a more accurate term than "mature". The 8200 is >> an unholy mix of consumer video and over-the-top digital design. >> They inherit vacuum-cleaner technology from Olivetti, origami >> techniques from U-matic, and really should have a fan on the >> card cage. > > Cool. :-) > >> An 8200 in *ideal* conditions (data centre) will give you long and >> reliable service. They are a poor choice for "normal" office >> environments. > > I've used plenty of these in datacenter environments and a few on home > systems over many years. They've been the most reliable tape storage > units in their price/capacity range that I've had the pleasure to use. Which others did you have the pleasure to use? > There have been little glitches along the way. When they first came > out, a very long time ago, they had a few problems here and there. > > They're quite solid now. Right. The newer Exabytes are a whole lot better than the old ones. In particular, it appears that the drum life has been extended by an order of magnitude. The 8200 is not a newer Exabyte, and if you buy a refurbished one, you're running the risk of drum failure in the short term. Note also that the drive firmware hides a lot of the retries. If you write to a drive like this, the data transfer light should be on more or less continuously. More likely, though, you'll see it go off from time to timee while the drive corrects write errors. This is transparent to the system. > I like being able to buy tapes at the corner drug store if I need to. > Unlike the newer, higher capacity Exabytes the 8200's were designed to > use consumer video tapes. (The newer ones require `data quality' tapes.) You can set the new ones to use consumer tapes, too, I think. Since the tapes are no cheaper, and the dropout rate is much higher, I can't see any reason to do this. I strongly recommend buying data grade tapes. > Two Gigs is not a lot of storage these days, but it's enough for many > home and small business situations. Putting 2 Gigs on the same realestate > that now holds 7 Gigs allows for a lot of redundancy. If the heads are capable of 7 GB, sure. In fact, the dropout rate is higher on the older drives. > I've got some eight and 10-year old tapes written on various drives > that are still readable today. Even readable on the new high-capacity > drives. Amazing. That doesn't surprise me. > No doubt there will soon be some higher capacity drives that are > as reliable and as inexpensive to use (media is part of the cost.) > Just not yet. What about DDS-2? You can get up to 7 GB on a 120m tape, and the units cost in the order of $700 new. DDS-3 will store still more, but they're also more expensive. In general, I'd say that the serious (as opposed to high-end) tape market is dominated by helical scan units based on consumer cartridge formats. Exabyte is based on 8mm video tape, and DDS is based on DAT (digital audio tape). In each case, the medium cost is low and the data capacity is between 2 and 14 GB. Both systems offer data compression, which in my experience (including backing up a lot of gzipped files) gives a storage improvement of about 90%. DDS drives tend to be cheaper, possibly because of the number of manufacturers out there. The reliability of *all* helical scan drives used to be barely acceptable, and has since got much better: as a result, I don't recommend buying older helical scan devices. Greg -- 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-hardware" in the body of the message
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