NFS as RootDevice for >=2 mics at one node

[d06pbiu_e_]

Hello everyone!

Can I use one nfs root export for two or more mic devices? I want to share ONE root nfs between all my mics at one node. Is it possible?

Thanks.

[Frances_R_Intel]

No, not really.

Unless you changed them, most of the files are the same regardless of which coprocessor you use. However, if you look in /var/mpss/mic0, /var/mpss/mic1, etc., you will find files that are specific to each coprocessor. Some of the files in those directories can match from coprocessor to coprocessor, if you want them to - such as etc/passwd - but some of them cannot, no matter what you do - such as etc/host or etc/network/interfaces. In addition, some directories - such as var - are actively being changed while the system is running and must be separate physical locations.

So, a straight forward answer is no. If you are an experienced cluster administrator or happen to have one immediately to hand, you might be able to make a base root image and use that to construct a specific root file system similar to how it is done for nodes in a cluster, but if you don't know what you are doing, you could cause yourself horrible problems and ultimately, you will still end up with unique directories on your host (or where ever you are mounting from) for each coprocessor.

[jimdempseyatthecove]

>>/var/mpss/mic

Francis, could the pertinent paths have /var/mpss/$(mic)

Or

export mpss = /var/mpss/mic0

IOW in the same manner as you would for INCLUDE, LIB, ...

Jim Dempsey

[Frances_R_Intel]

Jim,

I'm not quite sure I understand, so I am probably missing your point, but I don't think that helps.

• To NFS mount the root file system on the coprocessor, you must have a directory on your NFS server that contains exactly what you want in the root directory on the coprocessor.
• The contents of that directory will typically be the files from initramfs-knightscorner.cpio.gz (the generic root file system that is the same for all coprocessors) plus the files from /var/mpss/mic0 copied over what came from the generic version of the root. So, the contents of the etc directory will be a combination of the generic etc files and the mic0 specific etc files. 

Frances

[jimdempseyatthecove]

Francis,

I am sure you are familiar with

export LD_LIBRARY_PATH=SomewhereWhereYouPlacedTheLibraryFiles

I was suggesting to use a similar technique for the /var/mpss/mic0 or mic1...
But this requires the utilities to use environment variables, which they might not be programmed to use.

This morning, I thought of an alternate possibility. That is for the directory on the server, which is to be mounted as the root for the MIC, does not contain the MIC specific files, rather it contains a symbolic link to those files, and those links vary dependent upon the targeted MIC.

IOW the mounted root (different for each MIC), contains symbolic links to common files or whichever version of the MIC dependent files and folders. This would eliminate the duplication of files (at the expense of folders containing symbolic links). The end user should be able to do this(though an Intel supplied create mount folder for MICn: would be useful)

Jim Dempsey

[Frances_R_Intel]

Right. You would want only one copy of the base files and to have some way to use that one copy to create separate coprocessor root directories on the host. I'm sure an experienced cluster administrator would know how to do this with no problem but, unfortunately, I am most definitely not an experienced cluster administrator.