backing up to another machine

[nlfarr]

I have a DLT tape drive on one machine on my network and I want to use another machine to backup to it. But I'm having difficulty accessing the device from the second machine. Any suggestions?

[genlee]

You can do this a lot of ways.
tar- can backup to a remote tape drive
scp- to copy the data over then write to tape
nfs- mount the data you want backed up and write it to tape
rdump- dump data to a remote device
I am sure there are many other ways but I think any of those should be easy to do.

[nlfarr]

Ok, now I'm having difficulty using tar across the network. I believe the .rhosts is correct, but I'm just getting connection refused error when tar tries to run. Is there some other network setting on the tapehost that needs to be set?

[genlee]

Are you connecting with a valid user on the tapehost and could you paste the line you are using?

[nlfarr]

Ok, here is my command and the error that follows:

tar -tvf nlfarr@HOSTNAME:/dev/st0
HOSTNAME:Connection refused
tar: nlfarr@HOSTNAME\:/dev/st0: Cannot Open: Input/Output error
tar: Error is not recoverable: exiting now

[genlee]

Try something like this. I suggest your get a program called buffer because your tape needs to be fed data at constant speeds which just sending over ethernet can't garuntee.

tar c your.files | ssh -l someuser HOSTNAME "buffer -o /dev/st0"

[Dolda2000]

ssh is a truly wonderful program. However, genlee, doesn't it look better (purely cosmetically, I agree, but these things are important =) ) with someuser@HOSTNAME instead of -l someuser HOSTNAME? By the way, genlee, while we're at ssh, do you know how much overhead (on the net, not CPU) the encryption generates?

nlfarr, I hope you weren't serious with actually writing HOSTNAME (I hope you had replaced HOSTNAME with the actual name of the host)? Not that I think you did that, but I have to check anyway.

[genlee]

Dolda that probably depends on what type of encryption you use. I am sure the size of the encrypted data varies(always larger then source though) and the overhead is probably also dependant on the encryption method. I was told that generally you want to add an extra 100 bytes of overhead per packet with encrypted data. Ssh can compress the overhead from the encryption to squeeze some more data in there. I doubt most users will never notice this except in a large scale enviroment where everyone is encrypting their data. Then I would go to other methods of encrypted vpns like IPSEC which would encrypt on the ip layer and would offer less overhead. Also I remember seeing somewhere that they tested transfer speeds and rc4 cipher was the fastest.

[nlfarr]

Dolda - yes, I just wrote HOSTNAME in the post for generality's sake

genlee - I tried your command, but I got a:
buffer: command not found
I'm guess buffer is a command that I don't have.

I'm using Redhat 7.1

[genlee]

Yes I told you to install it Go to rpmfind.net and get it that is if you have mandrake or redhat. If not, just go to freshmeat and get the source.