[lug] Reserving part of a file system -- quotas or something else

[David Ahern]

On 11/08/10 15:03, Vince Dean wrote:
> I have a system on which I would like to reserve a certain amount of
> disk space for certain high-priority jobs, allowing all the users to
> fight over the rest.  The machine runs a variety of research, ad-hoc
> programs, alongside some high-priority production jobs.
> 
> Quotas sound attractive, but it's not obvious how to use them for this
> purpose.  I could assign a quota to each user, but that would be far
> more specific than I need.  I want either to reserve X Tbytes for one
> use , or else limit the sum of all the other uses to Y Tbytes. I don't
> need to manage quotas for each user.
> 
> One possibility would be to reserve an entire RAID, or an entire file
> system for the production jobs.  This would work, but would limit our
> future flexibility.
> 
> We have suggested using logical volume management to create the
> partitions and to re-size them if necessary.  The system administrator
> likes to use LVM for the initial setup of a system, but he is reluctant
> to resize a logical volume, for fear of catastrophic data loss.  Is that
> a reasonable fear?
> 
> Any suggestions?  Assigning entire machines or RAIDs to the production
> jobs would certainly solve the problem, and might
> be a better use of our time and money, but I would like to explore other
> options.  Am I overlooking an easy solution?

If it's a local filesystem using ext2, ext3 or ext4 you can reserve
filesystem blocks (tune2fs -m) and create a group for the users and set
the group for the reserved blocks (tune2fs -g).

David


> 
> Thanks,
> Vince Dean
> 
> 
> 
> 
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