I have a lot of image data on a remote server that I need to copy over to a local drive. The local drive writes data off to tape after 30days, and so it is important that the data is kept together in convenient chunks otherwise it can end up on multiple tapes and take several days to retrieve. To do this I ssh into the remote server, tar up each image sequence into a tarball, and write it to the local drive using CPIO. The result is I have my image sequence on the remote server, and the tar file locally.
What I want to do:
Check that the tar file contains everything that it is meant to contain. I believe using the tar --compare flag is the way to go, however I am having trouble figuring out how to use --compare to compare a local tar file to the source files on a remote server via ssh.
So far I think I can run the command locally using the following:
# Somehow tell it the files are located across an ssh connection
tar --compare --file=test.tar -C
But I don't know how to do the last part.
I have an SSH key setup with the remote server so I do not need to enter a password.
Alternatively if you have another method of doing this comparison I would love to hear it.
Related
How would you, in Ansible, make one remote node connect to another remote node?
My goal is to copy a file from remote node a to remote node b and untar it on the target, however one of the files is extremely large.
So doing it normally via fetching to controller, copy from controller to remote b, then unarchive is unacceptable. Ideally, I would do from _remote_a_ something like:
ssh remote_b cat filename | tar -x
It is to speed things up. I can use shell module to do this, however my main problem is that this way, I lose Ansible's handling of SSH connection parameters. I have to manually pass an SSH private key if any, or password in a non interactive way, or whatever to _remote_b_. Is there any better way to do this without multiple copying?
Also, doing it over SSH is a requirement in this case.
Update/clarification: Actually I know how to do this from shell and I could do same in ansible. I was just wondering if there is a better way to do this that is more ansible-like. The file in question is really large. The main problem is that when ansible executes commands on remote hosts, then I can configure everything in inventory. But in this case, if I would want a similar level of configurability/flexibility when it goes to parameters of that manually established ssh connection I would have to write it from scratch (maybe even as an ansible module), or something similar. Othervise for example trying to just use ssh hostname command would require a passwordless login or default private key, where I wouldn't be able to modify the private key path used in the inventory without adding that manually, and for ssh connection plugin there are actually two possible variables that may be used to set a private key.
Looks like more a shell question than an ansible one.
If the 2 nodes cannot talk to each other you can do a
ssh remote_a cat file | ssh remote_b tar xf -
if they can talk (one of the nodes can connect to the other) you can launch tell one remote node to connect to the other, like
ssh remote_b 'ssh remote_a cat file | tar xf -'
(maybe the quoting is wrong, launching ssh under ssh is sometimes confusing).
In this last case you need probably to insert some password or set properly public/private ssh keys.
I am doing an intensive computing project with a super old C program. The program requires a library called Sun Performance Library which is a commercial ware. Instead of purchasing the library by myself, I am running the program by logging onto a Solaris machine in our computer lab with the ssh command, while the working directory to store output data is still on my local Mac.
Now, a problem just occurred: the program uses large amount of disk space to save some intermediate results and the space on my local Mac is quickly filled (50 GB for each user prescribed by the administrator). These results are necessary for the next stage of computing and I cannot delete any of them before it finally produce the output data. Therefore, I have to move the working directory to an external hard drive in order to continue. Obviously,
cd /Volumes/VOLNAME
is not the correct way to do it because the remote machine will give me a prompt saying
/Volumes/VOLNAME: No such file or directory.
So, what is the correct way to do it?
sshfs recently added support for "slave mode" which allows you to do this. Assuming you have sshfs on Solaris (I'm not sure about this), the following command (ran from your Mac) will do what you want: dpipe /usr/lib/openssh/sftp-server = ssh SOLARISHOSTNAME sshfs MACHOSTNAME:/Volumes/VOLNAME MOUNTPOINT -o slave
This will result in the MOUNTPOINT directory on the server being mounted to your local external drive. Note that I'm not sure whether macOS has dpipe. If it doesn't, you can replace it with one of the equivalent solutions at How to make bidirectional pipe between two programs?. Also, if your SFTP server binary is somewhere else, substitute its path.
The common way to mount a remote volume in Solaris is via NFS, but that usually requires root permissions.
Another approach would be to make your application read its data from stdin and output its results to stdout, without using the file system directly. Then you could just redirect the data from/to your local machine through ssh. For instance:
ssh user#host </Volumes/VOLNAME/input.data >/Volumes/VOLNAME/output.data
I have a server (Machine A) that receives uploads throughout the day from other machines. I have a script running on another internal server (running as cron - Machine B) that uses rsync to pull these files onto itself and remove the originals on Machine A. Some of these uploads last an hour or more.
How do I use rsync so that it won't attempt to copy files that are currently uploaded (being written to)? I don't want it to pull partial uploads and then attempt to process them.
I'm using Ubuntu 10.04 64-bit on both machine A & B.
In order to make incremental baclups in rsync, you should put the --update or -u option. The only situation in which the a file existing in the receiver will be updated is when the archive exists and has the same timestamp in both ends but the size differs.
About the partial updates, all the temporary uploads are stored in a temporary archive and then moved to the dest directory when uploaded. you can use the --partial in case of a rsync or network problem, this will resume the partial updates next time you execute the sync again.
You can check the whole options from this man page.
I have a folder with 30000 files. I want to copy 1000 files a time via SSH to another folder. I need to do that cause my script is timing out when I try to run it on all 30k.
Is that possible?
EDIT
Based on the comments.
I connect via putty. The script is executed from the user by clicking a button and it not the problem. I just want to move the files in batches and I don't want to do it via ftp.
Like the LIMIT command in SQL (LIMIT 0,1000 or LIMIT 1000,2000)
The best way to copy over ssh is by using scp (pscp in putty)
pscp.exe -r somedir me#server:/data/vol1
pscp.exe uses all settings from putty including authentication keys.
Need to transfer 1 file from old host with no SSH access to a new host in which I do have SSH access. Having a hard time figuring this out. Looking for a simple answer if there is one. And also trying to avoid the slow upload times from my local machine, hence the reason for server to server transfer needed.
Are you able use FTP? You could use that to transfer the files.
If you have the URL of the file you want to move from your old host, you can use the wget command in your SSH terminal. You can use this for any file extension, or folders if you want.
For example, if you want to move http://www.yourhost.com/file.zip to your new host, you would SSH into the folder you want to download move this to, and type:
wget http://www.yourhost.com/file.zip