Article 128184 of comp.os.vms: Newsgroups: comp.periphs.scsi,comp.arch.storage,comp.os.vms,vmsnet.misc Path: nntpd.lkg.dec.com!pa.dec.com!decuac.dec.com!haven.umd.edu!news.umbc.edu!europa.chnt.gtegsc.com!cantaloupe.srv.cs.cmu.edu!das-news2.harvard.edu!oitnews.harvard.edu!rutgers!njitgw.njit.edu!tesla.njit.edu!syshaf From: syshaf@tesla.njit.edu Subject: Questions about DAT drives, DDS formats & tapes, and HP drives Message-ID: <1995Aug29.120238.1@tesla.njit.edu> Followup-To: comp.periphs.scsi Keywords: DAT, 4mm, tape, HP, 35480A, C1533A, VMS Lines: 80 Sender: news@njit.edu Nntp-Posting-Host: tesla.njit.edu Organization: ÿÿÿÿ Date: 29 Aug 95 12:02:38 EDT Lines: 80 Xref: nntpd.lkg.dec.com comp.periphs.scsi:44035 comp.arch.storage:7514 comp.os.vms:128184 vmsnet.misc:4309 I am one of several system managers at a university computing center. I am trying to get more information about, and some answers to questions about 4mm DAT tape drives used for backups of various UNIX and VMS systems via SCSI-2 bus (no PC's - yet 8^) ). We have several drives in-house and have been using them for backups for about 2 years now. We settled on the 4mm DAT tape format after using various others, including IBM 3480 cartridges and 8mm tapes, and now have a library of several hundred 4mm DDS tapes; most are MRS. We backup many Gigabytes of storage on various systems and are always looking for better ways and to reduce the amount of time spent on backups. We currently have a DEC TLZ04 (SONY model ?? inside) attached to a DEC ULTRIX system, and several OEMed HP35480A drives attached to various UNIX systems (SUN and DEC) and DEC VMS systems. Most of the drives see several hours of use each night as various file systems are backed up on a rotating basis. The HP drives are about 2 years old (see below) and the DEC TLZ04 slightly older. The DEC TLZ04 (SONY) is a DDS-1 drive; no compression. The HP35480A is a DDS-DC drive; compression configurable. I have several questions about the current and new technologies in this area and would be grateful for any info which anyone can supply, but please, facts only - not speculation. 1. We have seen the least amount of trouble with the DEC TLZ04 drive. To the best of my knowledge, all of the HP35480A drives have had problems at one time or another and have been repaired by our maintenance contractor (the way I understand it, they take the drives back to their shop, remove the drive from the case, and return them to HP for refurbished drives after which they are reassembled and returned to us). HP will not deal with us directly (?), only through the maintenance contractor. Typical problems with the HP drives include: write problems, read problems, tape stuck in mechanism, and various springs etc. expelled from the drive (when this happens, we take drive out of service as it would be playing Russian Roulette to load a tape; almost a sure thing tape will jam in mechanism). Drives usually last between 6-9 months before problems like this develop. Are problems like this typical? What are your experiences? 2. Due to carelessness upon our part and our maintenance contractor, the proper configuration switch settings for the various systems were lost. Also, the company from whom we purchased the drives appears to be out of business (hazards of dealing with low bidders) so we can't contact their tech support, who originally configured the drives. We need settings for 3 (maybe 4) basic setups: DEC VMS, DEC ULTRIX, SUN (both SUN/OS and SOLARIS if they're different). Yes, I have both the HP35480A product description and the HP DDS configuration guide (note: a manual written by someone who knows what to do for someone who already knows what to do, i.e. very poor descriptions and definitions, unless you are one of the originators of the SCSI standards 8^) ). I also understand, via other info received and practical experience, that the firmware level of the drive makes a difference to DEC VMS. Is this true, what level is needed, and how can I, as a user, determine a particular drive's firmware level? Does this also affect UNIX setups? 3. We may need a source of additional/replacement drives. Now that HP has come out with the C1533A DDS-2 drive, are the 35480A drives still in production? Or are distributors left with "just what's in stock"? 4. DEC has the TLZ06 drive which is DDS-DC compliant; whose drive is it? (SONY model ?? or HP model ??) Anyone who owns one care to comment? What about the newer TLZ07; I know it is DDS-2 compliant; whose drive? (SONY or HP - model ??) Again, anyone who has one or used one care to comment? 5. Can a DDS-2 compliant drive write in DDS-1 or DDS-DC format (I presume it can read them, to be backward compatible)? Can the HP 1533A do it? Is it software configurable, hardware configurable, or both? As I understand it, the compression algorithm for DDS-DC and DDS-2 is the same; true? 6. I have seen info to the effect that a 120 meter DAT tape is unusable in a DDS-DC or DDS-1 drive; of course I previously saw that a 90 meter tape was unusable in a DDS-1 drive, which I know to be false. Can the 120m tape be used in a DDS-DC or DDS-1 drive? 7. What about a DDS-2 drive writing to a 60m or 90m tape? Does tape have to be blank or degaussed? 8. This is probably our biggest concern: For compatability reasons, can a DDS-DC drive read a DDS-2 tape? I understand the compression is the same for both, and know the DDS-2 drive produces narrower tracks/tracks closer together. Will the DDS-DC drive tolerances allow reading the DDS-2 tape? I realize this has been rather lengthy, but any info obtained will be greatly appreciated. -- Henry Frystak New Jersey Institute of Technology System Administrator Computing Services Department VAX/VMS USENET Newsmanager University Heights TESLA::SYSHAF Newark, New Jersey 07102 syshaf@tesla.njit.edu