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Rsync took over 10 hours today to transfer a 1GB file over the internet (from one Raspberry Pi to another. Are there any ways to speed this up?
rsync uses ssh to transfer files. Therefore what you want to do is speed up ssh. You can do that by changing the encryption method to a faster one such as arcfour or blowfish. You can do this by using the -e flag. For example
rsync -avt -e "ssh -c blowfish" user#dest:/remote/path /local/path
Personally I use blowfish but here is a benchmark I found real quick. Keep in mind this isn't going to make rsync super fast all of a sudden, but it could help if the bottleneck is the CPU on either side which is likely with embedded machines. Also keep in mind that your build of ssh might not have all the ciphers you see used elsewhere.
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If I have multiple tasks defined in my playbook, does ansible creates a separate ssh connection for each of the tasks. If yes, is that not a performance issue.
Because whenever I do a verbose o/p while i run the playbook, against each task i spot this.
"ESTABLISH SSH CONNECTION FOR USER: gparasha"
Am i wrong in my understanding.
By default, Ansible creates a new connection for each task. It takes advantage of SSH connection multiplexing to significantly reduce the amount of time required to establish a new connection.
If you enable the pipelining feature, then in many cases Ansible will be able to re-use a single ssh connection for multiple tasks (although in some cases it will still need to spawn a new connection).
To enable pipelining, you need the following in your ansible.cfg:
[ssh_connection]
pipelining = True
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I want to test some Ransomware. Therefore I wanna use VMware and create a virtual machine, where I can execute this software. I already deleted the Network device, so that no connection is possible between my computer and the VM. Do I need to know something more about it. Could it be possible that the virus breaks out and affects my PC?
Make sure that you are not playing around with Cerber 6 Ransomware because it has Anti-VM features that can easily bluff you when you are on the test. I just got to know the same from this post:http://ransomwares.net/cerber-6-ransomware/. I request you to read this post to know more about Cerber's new Anti-VM & Anti-Sandboxing features which makes it dangerous than never before!
Be sure to disable all shared folders. Also disable any CPU virtualisation acceleration, then you should be fine.
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What is the point of allowing ssh-keygen to generate empty passphrase keys when it is not recommended to use such keys for remote login? What situations would such keys be useful for?
The passphrase protects the key in its storage on your local computer.
Even without a passphrase, a key is still better than a password, as it can only be "stolen" if someone has physical access to your computer (or at least some kind of network access to the files on your computer), whereas a password can be brute-forced (or leaked from any number of places in case you re-use passwords).
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Closed 9 years ago.
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I am using scp to download millions of small files (100 - 1000 kb) files from my EC2 instances. scp seems to transfer one file at a time and does not utilize fully my 1 gbps connection.
Is there a more efficient way to download the files? For various technical reasons, achieving and downloading is not an option.
Take a look at rsync. It can also work through ssh.
If you are still able to use tar, but not able to create a tarball on the remote host, you can try something like:
ssh ec2instance "tar c /path/to/source" | tar x -C /path/to/destination
You can use the v option to tar, or the pipe viewer to get feedback on the transfer.
If the above is not an option either, try running several (a dozen) scp in parallel to reduce the effect of the overhead induced by many small files.
(Also make sure that the filesystem is not the bottleneck.)
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I'm trying to script a backup system for several servers, some Windows, some Linux. I'd love to be able to use rsync but I can't (at least not in all situations, since some servers I can't install rsync to, and some are Win servers).
I've tested with wget in FTP mode with the "timestamping" option, and it seems to work pretty well regardless of platform. Are there other options that may be more robust/reliable, that will do incremental backups regardless of platform?
Thanks for any ideas
You might try Unison.
http://www.cis.upenn.edu/~bcpierce/unison/
You definitely want to have a look at rdiff-backup. And Server Fault. ;)