3 ms·

Resiliency to your NFS server falling over is one. Sane atomic updates and locking is another.

by regularfry 13y ago

kbd 13y ago
Atomic updates on an NFS share can be achieved with renaming changed files into place, no?
- nknighthb 13y ago
  It sounds like you're expecting NFS to be a reliable, proven, high-performance technology. It's anything but. I've never encountered an implementation without horrible bugs, most commonly involving locking and atomicity issues. Things get oh-so-much worse if you have to mix implementations, and performance is always bad. I would never consider NFS an option in any production system. On a more general note, anything you build that relies on the particular semantics of any sort of traditional filesystem is sure to be wrong, either now or in the future when it needs to be run on a different filesystem. This is an area of software engineering that's a serious pain in the ass. Avoid it whenever you can.
vidarh 13y ago
HA NFS is not hard. Using DRDB to replicate the underlying block device, or Gluster to replicate the underlying filesystem, plus IP takeover or e.g. keeaplived is fairly trivial to set up. Running NFS on a single server is a bit like running one of these configuration management systems on a single server - they won't be resilient then either. Using Gluster directly is another easy way of getting resiliency. Atomic updates and locking is another matter, but for a lot of setups it's simply not needed.
- regularfry 13y ago
  Or you can run a single tool that is designed for this one job. Gluster in particular isn't a panacea for resiliency, you've got to really know where it departs from POSIX to not create problems for yourself.
  - Diederich 13y ago
    Are the GlusterFS people mistaken? http://gluster.org/community/documentation/index.php/GlusterFS_General_FAQ#What_file_system_semantics_does_GlusterFS_Support.3B_is_it_fully_POSIX_compliant.3F http://gluster.org/community/documentation/index.php/Gluster... "GlusterFS is fully POSIX compliant."
    - regularfry 13y ago
      Ooh, news to me. That certainly wasn't the case 2 years ago.

Resiliency to your NFS server falling over is one. Sane atomic updates and locking is another.

kbd 13y ago

Atomic updates on an NFS share can be achieved with renaming changed files into place, no?

nknighthb 13y ago
It sounds like you're expecting NFS to be a reliable, proven, high-performance technology. It's anything but. I've never encountered an implementation without horrible bugs, most commonly involving locking and atomicity issues. Things get oh-so-much worse if you have to mix implementations, and performance is always bad. I would never consider NFS an option in any production system. On a more general note, anything you build that relies on the particular semantics of any sort of traditional filesystem is sure to be wrong, either now or in the future when it needs to be run on a different filesystem. This is an area of software engineering that's a serious pain in the ass. Avoid it whenever you can.

vidarh 13y ago

HA NFS is not hard. Using DRDB to replicate the underlying block device, or Gluster to replicate the underlying filesystem, plus IP takeover or e.g. keeaplived is fairly trivial to set up. Running NFS on a single server is a bit like running one of these configuration management systems on a single server - they won't be resilient then either. Using Gluster directly is another easy way of getting resiliency. Atomic updates and locking is another matter, but for a lot of setups it's simply not needed.

regularfry 13y ago
Or you can run a single tool that is designed for this one job. Gluster in particular isn't a panacea for resiliency, you've got to really know where it departs from POSIX to not create problems for yourself.
- Diederich 13y ago
  Are the GlusterFS people mistaken? http://gluster.org/community/documentation/index.php/GlusterFS_General_FAQ#What_file_system_semantics_does_GlusterFS_Support.3B_is_it_fully_POSIX_compliant.3F http://gluster.org/community/documentation/index.php/Gluster... "GlusterFS is fully POSIX compliant."
  - regularfry 13y ago
    Ooh, news to me. That certainly wasn't the case 2 years ago.