[OpenAFS] volume size

[Andy Cobaugh]

On 2011-01-14 at 11:43, Lewis, Dave ( LEWIS@nki.rfmh.org ) said:
> Hi,
>
> I'm wondering what is a reasonable size for large AFS volumes. I
> understand that the maximum size of a volume is about 2 TB (assuming
> that the partition is at least that size). From a practical standpoint,
> is it reasonable to have a 2 TB volume? Should I expect any problems
> doing operations like bos salvage or vos move on large volumes?

We've been running with some data volumes in the TB range for a while now 
without problems. Biggest volume right now is ~3.2TB. Splitting these 
large volumes isn't very practical.

vos move will seem to take forever, but we've moved TB scale volumes 
without any problems.

You'll find, however, that around 2TB, some tools will start to report 
negative numbers for volume size, and you can't set a quotas bigger than 
2TB, so you get to set the quota to 0, disabling it entirely.

> For example, I'm wondering if bos salvage has a "harder" time with a few
> large volumes than with several smaller volumes. I figure that, with
> smaller volumes, internal inconsistencies that bos salvage fixes would
> be more isolated than with large volumes, and that that would be
> beneficial. But I don't really know.

salvages will take longer certainly, but it hasn't had any problems in my 
experience.

> Currently we mount 25 GB volumes in users' home directories for their
> image data, which grows a lot during data processing. Some users are
> starting to feel limited by 25 GB volumes, so I'm considering going to
> 100 GB volumes. I would appreciate any advice. Should large volumes be
> salvaged more often than small volumes?

Gee, how big are their homedirs then ;) Ours start out with a 50GB quota, 
with some hovering somewhere between 100-200GB.

Our rule for allocating space is, don't give them too much right away, or 
they'll use it up in no time. When most people hit their quota, they 
naturally find ways to work within their quota without having to ask for 
more space ;)

--andy