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Hey guys I'm looking for some help. I'm trying to get the data off of some old SDLT tapes probably 11+ years old. I don't know anything about them besides they were made on an irix system and I do not know which version. The backups were definitly not made with tar. When I try to use tar I get "doesn't look like tar format"

I was able to find out the blocksize I think using dd. I entered this:

dd if=/dev/st0 of=sometestfile ibs = 64

Then I increased the 64 by a factor of two until I didn't get the "cannot allocate memory" error. And the I got the blocksize to 4096 before it let me. anyway I tried a couple cpio and got weird stuff happening.

cpio -ivBc /dev/st0

this just blinked for a while then ran and nothing came out and it asked me to give afile name. Can someone give me some help or point me in the right direction??

A.Martinez
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1 Answers1

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First step is to ditch the tape. The last thing you want is a tape failure, and you have an older tape. So dd that thing to a file on a hard drive. ibs doesn't matter. Regardless of whatever you set ibs to, it won't change the output of dd.

Second, you should use something xxd to hex dump the beginning and end of the file. For example, xxd -l 120 -c 12 [filename] will display the first 120 bytes of the file and xxd -s -120 -c 12 [filename] will display the last 120 bytes. That might give you some clue as to what format the backup is.

longneck
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  • Hey great! the xxd -l 120 -c 12 /dev/st0 first few bytes were labled xfsdump. I didn't know irix used that. Thanks for the help I'm sure this will help me get in the right direction – A.Martinez Jun 24 '16 at 16:02
  • That makes sense. irix uses xfs. From teh wikipedia page for irix: "IRIX was the first operating system to include the XFS file system." – longneck Jun 24 '16 at 16:13
  • just by the way I was trying to dd the tape and it would'nt let me. The correct syntax would be dd if=/dev/nst0 of=/somedirectory // also Im not sure if you would know but do you think using xfsrestore on ubuntu 14.04 would still work with the xfsdump that irix used? – A.Martinez Jun 24 '16 at 23:38