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

[Maxwell Spangler]

On Mon, 2010-11-08 at 15:03 -0700, 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.

> 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.

> 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?

This is how many of us expect enterprise computing to develop in the
future and your requests now sounds a lot like what everyone else is
trying to do:

1) Setup a Storage Area Network (SAN) that consists of a large array of
hard drives connected to an intelligent disk controller which is then
connected to a dedicated high speed network.  On the SAN, from the total
amount of storage space available, slice and dice it to make storage
volumes (LUNs) that can be made available on the network to machines as
needed.

2) Place your applications within virtual machines based on how you
would like to balance them: customer, or priority, or queue, etc.  Use a
virtual machine manager that can move virtual machines easily from one
server to another.  This will let you move virtual machines of low
priority to slow, energy-efficient CPUs while moving other high priority
virtual machines (and their high priority applications) to faster more
expensive CPUs.

3) Because the storage is networked, your virtual machines can still
access all the data regardless of where they are physically running.
You can resize VMs, reallocate processors to VMs and reallocate storage
space as needed.

The only drawback to this is that its currently quite expensive but for
enterprise operations it can be worth it.

On a smaller scale, I would setup a few servers with LVM and beat on
them until you either trust them or find specific reasons not to.  Alot
of the functionality of a hardware SAN can be implemented with a low
cost server running Linux and some quality, commodity hardware.

-- 
Maxwell Spangler
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