mckay@mace.cc.purdue.edu (Dwight D. Mckay) (06/19/91)
Our 8mm tape drive has once again died. Twice in two years. Since we are starting to handle a sizable amout of data created by the X-ray instruments here, I'm considering adding a second drive. Should I add another exabyte (8mm) or start switching over to DAT (4mm)? As I understand it the *big* differences are: - Ignoring compression, 8mm has greater capacity then 4mm. - 4mm is faster on "seeking" files Suggestions? Comments from owners of 4mm or 8mm drives? BTW: This drive would be attached a VMS machine and used remotely via Multinet from UNIX machines. --Dwight D. McKay, Purdue University, Department of Biological Sciences --Office: LILY B-145, Phone: (317) 494-4481 --mckay@gimli.bio.purdue.edu
brack@agrajag.yorku.ca (Tony Brack) (06/26/91)
In article <13753@mentor.cc.purdue.edu>, mckay@mace.cc.purdue.edu (Dwight D. Mckay) writes: >> Our 8mm tape drive has once again died. Twice in two years. >> >> Since we are starting to handle a sizable amout of data created by the >> X-ray instruments here, I'm considering adding a second drive. >> >> Should I add another exabyte (8mm) or start switching over to DAT (4mm)? This involves your own personal preference... We have both here, mainly because we are concerned with being able to read from both media. The down side of this is you would have 2 single points of failure. The plus side is you can read/write both media types... Don't expect TONS of better reliability with the 4mm drives. SONY's have caused us grief on DEC/Mips offerings, largely due to ROM bugs and the like. Archive drives seem to work rather flawlessly, and are *much* cheaper... at least by our experience. >> As I understand it the *big* differences are: >> >> - Ignoring compression, 8mm has greater capacity then 4mm. >> - 4mm is faster on "seeking" files >> >> Suggestions? Comments from owners of 4mm or 8mm drives? 8mm drives have capacities of 2.3 or 5 GB depending on whether or not data compression is on, whereas DAT capacity is 1.2 & 2.0 GB respectively. One interesting device we use which is relatively cheap is DILOG's DAT stacker. It is about half-again the price of a SONY DAT, and allows you to serially run through 8 cartridges. Again, the down side is the SONY transport used internally. (No ROM problems on VAXen yet...ed) If you'd like numbers, we have 5 stackers backing up about 10GB apiece for full backups on weekends unattended. >> BTW: This drive would be attached a VMS machine and used remotely via >> Multinet from UNIX machines. Let me know how & if you get this working! We tried and it didn't under MultiNET V2.1. Too many problems with VMS unloading the tape drive after rdump (rmt) exited. In particular it would be nice to pay attention to tape labels, something VMS does poorly, but UNIX makes no attempt to do in any way shape or form.. (a little stab here). Seriously, though, I haven't checked if MultiNET 3.0 rmt is better documented than its predecessor was... it may be worth giving another stab! >> --Dwight D. McKay, Purdue University, Department of Biological Sciences >> --Office: LILY B-145, Phone: (317) 494-4481 >> --mckay@gimli.bio.purdue.edu -- Tony Brack ][ Usenet: ......!utzoo!yunexus!brack VMS & UNIX Technical Support ][ brack@outland.yorku.ca Computing & Communications Services ][ Bitnet: brack@yulibra York University. ][ Voice: (416) 736-2100 x22687 4700 Keele St. || North York, Ontario M3J 1P3 || What's this coming up... ... sure hope it's friendly!
de5@ornl.gov (Dave Sill) (06/26/91)
In article <1991Jun25.181021.7508@newshub.ccs.yorku.ca>, brack@agrajag.yorku.ca (Tony Brack) writes: > >8mm drives have capacities of 2.3 or 5 GB depending on whether or not >data compression is on, whereas DAT capacity is 1.2 & 2.0 GB respectively. Are you *sure* the EXB-8500 does compression? I thought it was just a higher density recording. If it does use compression, then one would expect the capacity to be significantly less than 5 GB when storing previously compressed files, but none of the literature I've seen has said anything about the capacity being variable. Anyone have a definitive answer? -- Dave Sill (de5@ornl.gov) Tug on anything in nature and you will find Martin Marietta Energy Systems it connected to everything else. Workstation Support --John Muir
jayl@bit.UUCP (Jay Lessert) (06/27/91)
In article <1991Jun26.120606.14138@cs.utk.edu> Dave Sill <de5@ornl.gov> writes: >Are you *sure* the EXB-8500 does compression? I thought it was just a We're getting ready to buy some EXB-8500's and have done the requisite market surveys, etc. The EXB-8500 uses improved head technology to write double the effective density ("two tracks", according to the Exabyte sales rep) and is truly 5GB, no compression. 5GB tapes written on an 8500 cannot be read by an 8200 (sorta like QIC150/QIC24), but 2.3GB tapes can be read by an 8500 with up-to-date firmware. In addition, a compression module is available for the 8500 (don't know if it's actually the same compression HW as the 8200) which gets you to 10GB (average), or so. Or 25GB if you work for Exabyte Marketing! :-) -- Jay Lessert {decwrl,cse.ogi.edu,sun,verdix}!bit!jayl Bipolar Integrated Technology, Inc. 503-629-5490 (fax)503-690-1498