Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!uunet!ibmpa!cslater From: cslater@ibmpa.UUCP (Charlie Slater) Newsgroups: comp.sys.ibm.pc.rt Subject: Re: dump command AOS4.3 w/ 6157 drive Message-ID: <3888@ibmpa.UUCP> Date: 7 Feb 90 23:45:34 GMT References: <7527@lindy.Stanford.EDU> Reply-To: cslater@ibmpa.UUCP (Charlie Slater) Organization: IBM AWD, Palo Alto Lines: 35 In article <7527@lindy.Stanford.EDU> CN.RNA@forsythe.stanford.edu (Richard Anderson) writes: > >I have a question regarding the "dump" command. The AOS4.3 >System Administration manual (which I have found very useful >and clearly written) has a chapter on Backup & Restore, in which >a refererence is made to the 6157 streaming tape drive, followed >by an example of the dump command: > > dump 0suf 2600 /dev/st0 /dev/rhd0a > >They use a value of 2600 ft for the length of the tape and accept >the default density of 1600. However, the DC6150 tapes I use on my >6157-002 drive are 600 feet long and have a density(?) of 12,500 >ftpi. Tape drives are not my specialty but I will give this a try. A more practical measure of the density is 12K bytes / foot. The type 2 drives write at a higher density, but it will be easier for users of dump to pretend the type 2 drives make their tapes twice as long. The example's use of 2600 is not appropriate for the streaming device. Dump's default length for a streaming tape in the BSD Tahoe release is 1700 feet. This is 450 feet times 4 tracks (presumably appropriate for Tahoe hardware). In IBM 4.3, the default length is 4000 feet (450 x 9). For a 600-foot tape with a type 1 (original model) drive, use 5400 (or 5300 if you are as paranoid as I am). If you have a type 2 (double density drive), you can specify 10000. At 12K bytes per foot, you can get 60 megabytes on a 600 foot tape (120 megabytes using a type 2 drive). This posting is based on my personal experience and examination of the dump source code. It does not represent the official postion of IBM. Any errors are my own responsibility. -- charlie slater uunet!ibmsupt!cslater (UUCP) cslater%ibmsupt@uunet.uu.net (Internet) cslater@ibmpa.tcspa.ibm.com (IBM internal internet)