Forum Rules and Etiquette

Our mission ...

This forum is part of our mission to promote the preservation of vintage computers through education and outreach. (In real life we also run events and have a museum.) We encourage you to join us, participate, share your knowledge, and enjoy.

This forum has been around in this format for over 15 years. These rules and guidelines help us maintain a healthy and active community, and we moderate the forum to keep things on track. Please familiarize yourself with these rules and guidelines.

Rule 1: Remain civil and respectful

There are several hundred people who actively participate here. People come from all different backgrounds and will have different ways of seeing things. You will not agree with everything you read here. Back-and-forth discussions are fine but do not cross the line into rude or disrespectful behavior.

Conduct yourself as you would at any other place where people come together in person to discuss their hobby. If you wouldn't say something to somebody in person, then you probably should not be writing it here.

This should be obvious but, just in case: profanity, threats, slurs against any group (sexual, racial, gender, etc.) will not be tolerated.

Rule 2: Stay close to the original topic being discussed
  • If you are starting a new thread choose a reasonable sub-forum to start your thread. (If you choose incorrectly don't worry, we can fix that.)
  • If you are responding to a thread, stay on topic - the original poster was trying to achieve something. You can always start a new thread instead of potentially "hijacking" an existing thread.

Rule 3: Contribute something meaningful

To put things in engineering terms, we value a high signal to noise ratio. Coming here should not be a waste of time.
  • This is not a chat room. If you are taking less than 30 seconds to make a post then you are probably doing something wrong. A post should be on topic, clear, and contribute something meaningful to the discussion. If people read your posts and feel that their time as been wasted, they will stop reading your posts. Worse yet, they will stop visiting and we'll lose their experience and contributions.
  • Do not bump threads.
  • Do not "necro-post" unless you are following up to a specific person on a specific thread. And even then, that person may have moved on. Just start a new thread for your related topic.
  • Use the Private Message system for posts that are targeted at a specific person.

Rule 4: "PM Sent!" messages (or, how to use the Private Message system)

This forum has a private message feature that we want people to use for messages that are not of general interest to other members.

In short, if you are going to reply to a thread and that reply is targeted to a specific individual and not of interest to anybody else (either now or in the future) then send a private message instead.

Here are some obvious examples of when you should not reply to a thread and use the PM system instead:
  • "PM Sent!": Do not tell the rest of us that you sent a PM ... the forum software will tell the other person that they have a PM waiting.
  • "How much is shipping to ....": This is a very specific and directed question that is not of interest to anybody else.

Why do we have this policy? Sending a "PM Sent!" type message basically wastes everybody else's time by making them having to scroll past a post in a thread that looks to be updated, when the update is not meaningful. And the person you are sending the PM to will be notified by the forum software that they have a message waiting for them. Look up at the top near the right edge where it says 'Notifications' ... if you have a PM waiting, it will tell you there.

Rule 5: Copyright and other legal issues

We are here to discuss vintage computing, so discussing software, books, and other intellectual property that is on-topic is fine. We don't want people using these forums to discuss or enable copyright violations or other things that are against the law; whether you agree with the law or not is irrelevant. Do not use our resources for something that is legally or morally questionable.

Our discussions here generally fall under "fair use." Telling people how to pirate a software title is an example of something that is not allowable here.

Reporting problematic posts

If you see spam, a wildly off-topic post, or something abusive or illegal please report the thread by clicking on the "Report Post" icon. (It looks like an exclamation point in a triangle and it is available under every post.) This send a notification to all of the moderators, so somebody will see it and deal with it.

If you are unsure you may consider sending a private message to a moderator instead.

New user moderation

New users are directly moderated so that we can weed spammers out early. This means that for your first 10 posts you will have some delay before they are seen. We understand this can be disruptive to the flow of conversation and we try to keep up with our new user moderation duties to avoid undue inconvenience. Please do not make duplicate posts, extra posts to bump your post count, or ask the moderators to expedite this process; 10 moderated posts will go by quickly.

New users also have a smaller personal message inbox limit and are rate limited when sending PMs to other users.

Other suggestions
  • Use Google, books, or other definitive sources. There is a lot of information out there.
  • Don't make people guess at what you are trying to say; we are not mind readers. Be clear and concise.
  • Spelling and grammar are not rated, but they do make a post easier to read.
See more
See less

Tapes: A few pointers when using SCSI/IDE tape drives on Debian Linux

  • Filter
  • Time
  • Show
Clear All
new posts

    Tapes: A few pointers when using SCSI/IDE tape drives on Debian Linux

    While I'm doing a bunch of tape work today, I thought I'd pass on some useful hints.

    First off, you really need to install the following packages: mt-st mtx lsscsi
    The first, mt-st, changes the "mt" command to support lots of additional options not present in the stock version. If you're going to write tapes, you need the capabilities.
    The second, mtx, contains the "scsitape" utility. I recently had to retrieve data from an 8mm tape that consisted of many files, each file starting with a 244-byte block, followed by 404 blocks of 6164 bytes. The standard "dd" utility isn't set up for this, but scsitape can transfer arbitrarily-sized blocks and this is what I used.
    The third, lsscsi, is useful for finding out where devices are. In particular, the "scsitape" utility requires not the name of the block device (e.g. /dev/st0), but its generic SCSI conntection (/dev/sgX).

    To make life easy, you probably should set the environment variable TAPE to the device name. Since I want control over tape positioning, I don't what automatic rewind at device close. For example, if the basic device is /dev/st1, I use /dev/nst1, which inhibits auto-rewind. So, to set the TAPE variable to this, I do:

    export TAPE

    Scsitape requires a generic scsi device name, so "lsscsi -g" might give an output like this:

    [0:0:6:0] tape EXABYTE EXB-8505 0052 /dev/st1 /dev/sg4

    Scsitape requires that you explicitly supply the generic scsi device, so you'd use "scsitape -f /dev/sg4 command" to access the drive. Here's an example of how to use the "command" part:

    I'm given an 8mm (Exabyte) tape from some sort of data collection setup. Said tape has no directory structure but is made up of many files consisting of one record of 244 bytes and 404 records of 6164 bytes (yes, Virginia, such things exist!). The standard utility "dd" is not set up to handle something like this, so it's scsitape. Note that since this is accessing a low-level interface, you have to have superuser privileges. To get a single file, I'd run the following:

    sudo /sbin/scsitape -f /dev/sg4 read 0 1 >file1.hdr
    sudo /sbin/scsitape -f /dev/sg4 read 0  >file1.dat

    The result would be two files, one of 244 bytes and the second of 2,490,480 bytes. For the remainder of the tape, write a bash script to generate names and run until no more data is transferred.

    If you do use "dd", note that dd transfers a single block of data in blocking mode as default behavior. On a streamer tape, this can be horrible, with the drive "shoe shining" after every block or so, particularly when writing. This is why you really need the "mt-st" package. Let's suppose that we're using the TAPE variable set up at the beginning of this past and we want to write a tape. The first task is to load a tape in the drive. Since I'm writing a tape with 512 byte blocks and want to do it at the highest density my EXB-8700 drive will support, I set things up this way:

    mt setblk 512
    mt setdensity 21

    The "setblk" is pretty obvious, but where did I get the number for the "setdensity". Unfortunately, this is where you have to do some digging. Tandberg Data, who owns Exabyte, has published a document that gives the various setting of the density argument--they're unlikely to be shared with non-Exabyte devices.

    After having set the density and physical block size, I can perform my copy onto the tape:

    dd if=myfile of=$TAPE bs=1M

    Why the "bs" specification? We already have instructed the low-level SCSI driver to write 512 byte blocks, so we can speed things up considerably by doing our I/O in megabyte chunks, which avoids "shoe shining".

    Finally, we can rewind the tape and unload it from the drive:

    mt rewind
    mt eject

    For those of you trying to get a handle on Linux and tapes, I hope this will get you started.
    Last edited by Chuck(G); November 30, 2021, 12:30 PM.
    Reach me: vcfblackhole _at_ protonmail dot com.



      Man, I haven't touched tape drives since... geeze, 2003? The company gave me enough money to buy a 20-slot LTO tape jukebox from Dell... and no more, so I pieced a clattering zombie of a backup system together using a Linux host. I was proud of it at the time but I don't think I can remember a thing about how I set it up or what software I used. (Finding something to run the tape robot felt like an achievement at the time.)
      My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs Also: Blogspot


        It always amused me that the original Star Trek TV series kept referring to "tapes". Lack of prescience, I suspect. Still, in 1966, we were still spinning a lot of tape (and cards).
        Reach me: vcfblackhole _at_ protonmail dot com.


          When I was a kid it bugged me that so many people insisted on referring to Atari 2600 cartridges as "tapes". (I mean, seriously, even grade schooler could tell you there wasn't any tape in those things. Maybe it was a regional thing?) Apparently the idea of calling a removable storage cartridge of any sort a "tape" was well engrained in the collective consciousness for a long time.
          My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs Also: Blogspot


            Consider the 60's-70's TV shows showing "computers". A few started out with unit-record gear (e.g. sorters, printers), then moved to blinkenlights and spinning tapes. A few showed only tape drives. Eventually CRT displays.

            Star Trek TOS and tapes
            Last edited by Chuck(G); November 30, 2021, 07:19 PM.
            Reach me: vcfblackhole _at_ protonmail dot com.


              Star Trek TOS did a fair job of emulating the look of near future computer hardware. The end result does make it appear that after the couple of wars in the future history that the technology base was reduced to the Kenbak-1 reading Zip disks.


                vinyl records? visiphone.png


                  Tape backup is no longer affordable for most home users (anything new is more expensive then dumping it on another drive or the cloud).
                  What I collect: 68K/Early PPC Mac, DOS/Win 3.1 era machines, Amiga/ST, C64/128
                  Nubus/ISA/VLB/MCA/EISA cards of all types
                  Boxed apps and games for the above systems
                  Analog video capture cards/software and complete systems


                    people at home never did backups, which is why just having some invisible hand take care of it for you is now the way things are.


                      Originally posted by Al Kossow View Post
                      people at home never did backups, which is why just having some invisible hand take care of it for you is now the way things are.
                      Some of us did.
                      PDP-8 and PDP-11 enthusiast. But enjoy most older PC stuff too.