Ubuntu – How to check hard disk performance

Actually FTP has quite an efficient data throughput rate once it gets going. The overhead that slows things down is with the getting a file downloading in the first place. That's not to say that there isn't a problem with Samba here. It should be performing nearly identically.

To be honest, I don't have much of a clue where you should start trying to fix this.

Ideally you'd be able to drop another computer in there with a reference install of Samba (eg Windows) and test that as both a client and server against the Ubuntu machines. Then you'd know which machine was the problem, if it was just one direction that was the problem and then you'd be able to report bugs based on this and/or find a workaround for the interim.

A while back I saw something about certain network hardware glitching under Samba. It was both switches and network adapters but I can't for the life of me find anything about it. It was probably such an edge case that it's not worth considering.

How about we sidestep Samba? FTP might not work but what about NFS? It probably has the highest transfer speeds out of the lot (in my experience) and it should handle rsync fine.

You could also look at FUSE-mounting the FTP server so rsync can bully it.

ReadyBoost improves things by caching boot files on media with fast access time. It's much like ureadahead but using an agile medium instead of just stacking the files on the boot disk. Whether or not it actually works better than something like ureadahead is highly debateable.

A Flash drive might have a lower seek time than a mechanical disk but throughputs are often very limited (there are exceptions of course: USB3 SSDs, for example). It's possible that by removing the seek element (as it does by stacking the files) ureadahead is faster because the drive has the faster throughput.

ReadyBoost has no effect on after-boot performance, IIRC, though it's concievable they might put some memory paging on there too if it's fast. You can put your swap on an external drive but that's only viable if the disk is faster, in both access and throughput.

In answer to your question: plugging a slow mechanical disk into a slow USB2 bus will give you no benefit other than extra disk space. Even if ureadahead could use it (which I don't think it can) any benefit would rely on the external drive having a higher throughput than your internal disk.

If that's the case (your internal disk is slow) you really want to consider upgrading it. Your primary disk should be the fastest permanent storage in your system. If you're considering an external swap, have a look at the prices of RAM. Stupidly high quantities are very cheap these days.