Date: Thu, 08 Nov 2001 11:48:54 +1100 From: Tony Landells <ahl@austclear.com.au> To: Odhiambo Washington <wash@wananchi.com> Cc: FBSD-Q <freebsd-questions@FreeBSD.ORG> Subject: Re: Backup Tapes - Advise sought Message-ID: <200111080048.LAA02290@tungsten.austclear.com.au> In-Reply-To: Message from Odhiambo Washington <wash@wananchi.com> of "Wed, 07 Nov 2001 16:21:26 %2B0300." <20011107162126.H66293@ns2.wananchi.com>
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wash@wananchi.com said: > I need to buy a tape drive. Some sales geek has suggested HP Surestore > DAT40 - a DDS-4 tape drive. I've gotten mixed up with this DDS and DLT > stuff. What's the difference? I am not quite familiar with tapes. > Does someone recommend something else different than the one here? I > also welcome any reasons supporting some particular type of tape > drive. It depends a lot on how much you want to backup, how much you want to allow for "future-proofing", and how big your budget is. The DDS tapes are very small, which is their biggest advantage ;-) We have a DDS-3 drive (I think) from HP in one of our NT servers. I don't have much to do with it (hence not being sure if it's DDS-3) but I know within three months of getting we had to replace the drive. Twice. Since the second replacement we've had 18 months trouble-free but still... Both DDS and DLT are getting to be fairly old technologies, and are having trouble squeezing in additional capacity to meet the growing amounts of data people want to back up. In comparing capacities, you also want to look at what data you're backing up, and what the uncompressed and compressed capacities of the tape drives are. We have a DLT 7000 which is backing up just over 70 GB on a database server. Note that 70 GB is the claimed compressed maximum for DLT-7000, but our database software reserves lots of space and doesn't compress data, which makes it a perfect candidate for compressed backups. A more realistic assessment for DLT-7000 is considered to be about 50 GB per tape. There is a slightly higher capacity DLT-8000, but again I refer to my claim that they're having trouble squeezing in extra capacity. The DLT-8000 standard arrived about two years overdue, and doesn't offer much over DLT-7000. I would suggest that the only point in going this path is to protect an existing investment. If you need good capacity (50 GB plus) and tapes that will be readable in drives you might have in a few years time (on the assumption that if you want ~50 GB now, in a few years that will have grown to 100+ GB) then you should look at a newer technology such as AIT or LTO (LTO is the "technology" used in Ultrium tape drives). The cartridges have a better uncompressed capacity, and the compression algorithm tends to work better (MUCH better) than DLT. Tony -- Tony Landells <ahl@austclear.com.au> Senior Network Engineer Ph: +61 3 9677 9319 Australian Clearing Services Pty Ltd Fax: +61 3 9677 9355 Level 4, Rialto North Tower 525 Collins Street Melbourne VIC 3000 Australia To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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