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I have an image server, this server contains disk images to be used by virtual machines. The server has to allow the runtime creation of new images, so iscsi is not good as it requires to restart the iscsi server in order to introduce a new target and I don't want that (I could't find any api to edit the /etc/iet/ietd.conf file either so it would be tricky too).

For this reason I am looking at nfs: I would mount this remote folder on each host and a new vm disk creation by the image server is supported as, from nfs point of view, it is equivalent to add a new file into the shared folder.

On a lan it works fine, but now that I have to extend my system to the internet I have these two doubts:

1- do nfs support a folder sharing over the internet? It seems to have been developed for LANs so I don't know how it deals with NATs, firewalls and stuff.

2- do nfs offer good performances? These vm images have to be used by virtual machines, so communication has to be pretty responsive.

If these two points are not satisfied can you also suggest me a good alternative?

closed as off-topic by Andrew B, dawud, MichelZ, Nathan C, krisFR Apr 12 '14 at 21:18

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    Disk I/O over the internet is not a good design. What is the actual problem you are trying to solve by doing this? – Andrew B Apr 12 '14 at 18:14
  • It is necessary to support live migration of virtual machines: the disk storage has to be shared across the internet. – user2358943 Apr 12 '14 at 18:17
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    Please don't mistake the following for rudeness: if you are considering virtual disk I/O over the internet, take a step back and hire a professional to help you. There are many "obvious" reasons in the professional IT field why this is a very bad design, and we cannot impart upon you a comprehensive education in disk I/O and network reliability. Either you have a reliable, privately routed network between these locations, or you don't. The internet cannot bridge that for you. – Andrew B Apr 12 '14 at 18:32
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NFS can run over the Internet, but not well. It's simply not optimized for the sub-par WAN links and possible traffic loss associated with it.

I agree with Andrew B on this one. There's usually at least a server on the same LAN segment for handling images in a given location. NFS is far too unreliable (any WAN-based system is) to be used for an active operating system image. You'd probably see a lot of corrupt copies if you tried it.

  • "any WAN-based system is" -- Yeah, that's ultimately what I was trying to get at. It's a problem rooted in the approach (trying to do this over WAN), not in selection of solution (NFS). – Andrew B Apr 12 '14 at 19:11
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    I've experimented with both NFS and iSCSI over the Internet, and the best I can say about either of them is that they were slow. Filesystems are generally not designed for high latency and get very upset if they don't get responses back very quickly. You can't beat the speed of light... – Michael Hampton Apr 12 '14 at 21:46

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