vbr.py and filesystems



Vertica 7.2 Documentation states that the only filesystems vbr.py can be used with are ext4 and nfs which seems strange to me. In my understanding nfs is not a filesystem by itsself but rather a transport mechanism to store data on a filesystem on (in most cases) a different computer. Does it matter which filesystem I use on the target ? Does it mean, making a backup on ocfs2 is not supported, but backing up via nfs to an underlying ocfs2 is - maybe even on the same host (node) ?





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    Yes, NFS is a specification, implementations could be different; hence it depends. Expectation here is NFS implementations adhere to the specification.


    The reason for explicitly specifying this is we got rid of hardlinks on backup hosts in 7.2. AFAIK protocol implementations are free to return an error if they don't support hardlinks. With 7.2, it doesn't matter as we don't use hardlinks anymore.

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    Thanks for your reply.


    Okay, nfs is a specfication, but its abilities depend on the underlying filesystem and/or operatingsystem - see hardlinks or the precision of timestamps. I hope we agrre here.  For me, it is a mismatch that the documentation explicitely requires ext4 (which is not available on SuSE 11.0, at least not writeable and thus unusable) but allows backups on any file system, as long as it is accessed via nfs. I can imagine that writing on XFS or ocfs2 might have issues, but how should they disappear when the same data is written by the nfs-daemon (on the same machine ?)


    After consulting the support I am writing my backups to an ext3 filesystem (I am using SuSE 11.0 :-( ) but would really like to safely write to my ocfs2 disks without losing support. If using nfs on loopback is an option, I would do that, but I am still not able to see the difference to direct writes.

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