Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!jarthur!nntp-server.caltech.edu!gumby!tim From: tim@gumby.cs.caltech.edu (Timothy L. Kay) Newsgroups: comp.periphs.scsi Subject: Re: High Capacity Tapes: Exabyte or DAT? Message-ID: Date: 29 May 91 00:26:38 GMT References: <29543@hydra.gatech.EDU> <9850023@hpcpbla.HP.COM> <1991May28.130950@anusf.anu.edu.au> Sender: news@nntp-server.caltech.edu Organization: California Institute of Technology, Pasadena Lines: 29 mbl900@anusf.anu.edu.au (Mathew BM LIM) writes: >I am new to this discussion so I may have missed the answer to the following >question. >One of our vendors has told me that the 5GByte figure on the capacity on the >newer Exabyte drives is achived by on board data compression and that the actual >capacity depends on the compressability of your data. So presumably the >actual capacity of a tape is anywhere from 2.3GBytes to 5GBytes. Is this >true? If it is, does anyone have any figures on what the "typical" capacity >is when backing up a "typical" filesystem? Your vendor is confused. It is true that Exabyte now offers compression capability with their EXB-8200-SX unit, and that will allow you to store approximately 5 GB on a tape (assuming 2X compression). HOWEVER, Exabyte ALSO has an EXB-8500 which stores 5 GB UNCOMPRESSED. You can get that with a compression chip (or compress the data on the host, and then you'll be able to put 10 GB on a tape (again assuming 2X compression). If your vendor is saying that you should get a DAT, consider that it is quite easy these days to buy a 2.3GB EXB-8200 drive (bare) for about $1800. I just hooked one up to my Iris 4D-80GTB trivially, and it is working nicely. If you ask via email, I'll send you the name of the vendor. Tim