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I have an HPC including a server and about 20 diskless computing nodes. The server has a swap partition. I wonder if I could use this swap partition over network (ie. using NFS) to be used by computing nodes. I know this would cause serious speed reduction, but as nodes need small amount of swap for just some seconds, it worth to use this strange type of swapping.

P.S: nodes don't have HDD and they have the maximum supported memory(RAM).

P.S: Here:http://www.tldp.org/HOWTO/Network-boot-HOWTO/x542.html, it is said that I can do it for one remote workstation, but it doesn't say anything about having many workstations simultaneously.

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No you can not share a swap partition (or a swap file) between different active hosts. Linux' paging is not programmed in a way that expects that the swap partition is accessed concurrently from different systems.

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you shall get an error like this, cause kernel needs to write to swap-file directly

  swapon: /mnt/shady/swapfile: swapon failed: Invalid argument

It's not possible to directly write to an NFS mount without going through the file-system you might be able to use i SCSI to do this, but the real question is whether it's worth it at all.

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  • thanks for your reply, but as I searched, I can use swap partition over NFS(http://www.tldp.org/HOWTO/Network-boot-HOWTO/x542.html), but only for one remote system. As I mentioned, I have a number of computing node and I wonder if I can use only one swap space shared for all of them. – mohammadh montazeri Jan 17 '16 at 11:14
  • wow fascinating stuff as i said nfs swap cant be done unless that patch,other one with nbd protocol i have to try this thanks for the link, amazing stuff – Shantanu Bedajna Jan 17 '16 at 11:45
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Sharing a swap partition between more than one concurrently running system is an exceedingly bad idea. The system swaps memory pages on and off this area. Consider what would happen if system A swaps out some pages, system B also does this with no knowledge of system A, System A retrieves it's pages (mangled by system B).

The space can be shared if you can guarantee that only one OS will use it at a time, but that doesn't appear to be your use case. If the nodes have the maximum supported memory, the real question is do I need swap at all?

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