karl@forest.gsfc.nasa.gov (karl anderson) (01/10/91)
It seems that there is no standard format for 8mm tapes, so that an 8mm tape written on, say, a DECstation 5000 cannot be read on a Sun and vice versa. I think 1/4" formats are more standardized (QIC and all that). Am I right - can a 1/4" tape written with tar, cpio, dd or dump on a DECStation be read on a Sun? Email unless you think the net would like to know. TIA. Karl A. Anderson | Internet: karl@forest.gsfc.nasa.gov NASA/GSFC code 923 (STX) | voice: (301) 286-3815 Greenbelt, MD 20771 | #include "std_disclaimer"
NAGY@nagy.fnal.gov (Frank J. Nagy:VAX Guru,Wizard&Loose Cannon) (01/10/91)
>>It seems that there is no standard format for 8mm tapes, so that >>an 8mm tape written on, say, a DECstation 5000 cannot be read on >>a Sun and vice versa. Actually, there are two basic formats for 8mm tapes (all the 8mm drives can read/write either, its up to higher level software to select the correct mode). The drives can write in either variable block or fixed block mode; tapes written in one mode cannot be read in the other. All VAXes (VMS) write tapes in variable block mode for instance since this provides the correct emulation of normal magnetic tape operations (user records can be any size). In fixed block mode, records written to the tape must be multiples of 1024 bytes (the basic stripe size of data on the tape - in variable block mode the drive firmware manages fitting user data to/from the 1024 byte stripes). We've discovered than some UNIX systems (Sun's for instance) only provide [at this time] drivers that use fixed block mode. Other system, such as SGIs, provide drivers that handle either fixed or variable block mode. We've had no problems interchanging 8mm tapes here at Fermilab between numerous systems: VAXes running VMS with several different 8mm systems from different vendors [8mm on VS3100 SCSI, QBus-to-SCSI and even HSC-based 8mm drives] between themselves and with SGIs (Personal Irises and several 4D/240s, using variable block mode) and a DECStation 3100. = Dr. Frank J. Nagy "VAX Guru & Wizard" = Fermilab Computing Division/Distributed Computing Dept/Special Projects Grp = HEPnet/SPAN: FNDCD::NAGY (43123::NAGY) or FNAL::NAGY (43009::NAGY) = Internet: NAGY@FNAL.FNAL.GOV = BitNet: NAGY@FNAL = USnail: Fermilab POB 500 MS/234 Batavia, IL 60510
Rudy.Nedved@rudy.fac.cs.cmu.edu (01/11/91)
I use 8mm tape drives on DECstation 3100, Sun3s and DEC VAX. I have had no compatibility problems. However each system has presented problems with basic reading and writing of tapes. After fixing all these software problems, everything is happy. -Rudy
guy@auspex.auspex.com (Guy Harris) (01/12/91)
>We've discovered than some UNIX systems (Sun's for instance) only >provide [at this time] drivers that use fixed block mode. I think at least some of the SCSI drivers in SunOS 4.x support variable-block mode.
prc@erbe.se (Robert Claeson) (01/15/91)
In article <25456@adm.brl.mil>, karl@forest.gsfc.nasa.gov (karl anderson) writes: |> It seems that there is no standard format for 8mm tapes, so that |> an 8mm tape written on, say, a DECstation 5000 cannot be read on |> a Sun and vice versa. No. There are two standard formats, but Sun's driver can only handle one of them. |> I think 1/4" formats are more standardized (QIC and all that). Am I right |> - can a 1/4" tape written with tar, cpio, dd or dump on a DECStation be |> read on a Sun? Yes, but you'll have to find a DECstation with a standard QIC drive first. All DECstation's I've seen comes with drives for DEC's very own TK50/TK70 cartridges. -- Robert Claeson |Reasonable mailers: rclaeson@erbe.se ERBE DATA AB | Dumb mailers: rclaeson%erbe.se@sunet.se Jakobsberg, Sweden | Perverse mailers: rclaeson%erbe.se@encore.com Any opinions expressed herein definitely belongs to me and not to my employer.