How to generate a large file allocating space

[Andreas Dilger]

On 2010-11-01, at 00:14, Alex Bligh wrote:
> --On 1 November 2010 00:13:33 -0600 Andreas Dilger <adilger at dilger.ca> wrote:
>> Hmm, why not simply use a cluster filesystem to do this?
>> 
>> GFS and OCFS both handle shared writers for the same SAN disk (AFAIK),
>> and Lustre uses ext4 as the underlying filesystem, and though it doesn't
>> allow direct client writes to the same disk it will allow writing at 95%
>> of the underlying raw disk performance from multiple clients.
> 
> Essentially because none of them do exactly what I need them to do,
> so I am reinventing a slightly different wheel...

Personally, I hate re-inventing things vs. improving something to make it do what you want, since it means (probably) that your code will be used by you alone, while making an improvement to an existing cluster filesystem will both meet your needs and allow others to benefit as well.

What is it you really want to do in the end?  Shared concurrent writers to the same file?  High-bandwidth IO to the underlying disk?

Cheers, Andreas