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From: Albert on 16 Jun 2010 17:39
I want to be able to find the free disk space for a network drive. Ideally a platform independent solution would be best. At a minimum this needs to be done without admin rights on Windows and on Linux. I have not had any luck.
The best i have done so far is parsing S=evalc('system(''dir'')')
Anything better?
Thanks.
-yot
From: Walter Roberson on 16 Jun 2010 17:47
Albert wrote:
> I want to be able to find the free disk space for a network drive.
> Ideally a platform independent solution would be best. At a minimum
> this needs to be done without admin rights on Windows and on Linux. I
> have not had any luck.

There is no platform-independent answer for this, as some systems have
"infinite" disk storage (managed through techniques such as tape migration.)

The amount of space that is free _now_ is almost never the amount of space
that you can write to.

If the question "can I produce a file this big?" then fopen() the file for
"a+", fseek() to the offset-1, fwrite() a byte and check to see if the fwrite
worked; if it did, then fseek() to the beginning of file and go ahead and use
the file. This will, however, not work if your file system knows about "holes"
and if your file system detects this case as signaling that you want hole to
be made.
From: Albert on 16 Jun 2010 18:09
Walter Roberson <roberson(a)hushmail.com> wrote in message <hvbgth$6u9$1(a)canopus.cc.umanitoba.ca>...
> There is no platform-independent answer for this, as some systems have
> "infinite" disk storage (managed through techniques such as tape migration.)
>
> The amount of space that is free _now_ is almost never the amount of space
> that you can write to.
>
> If the question "can I produce a file this big?" then fopen() the file for
> "a+", fseek() to the offset-1, fwrite() a byte and check to see if the fwrite
> worked; if it did, then fseek() to the beginning of file and go ahead and use
> the file. This will, however, not work if your file system knows about "holes"
> and if your file system detects this case as signaling that you want hole to
> be made.

The questions is more: I want to run a process that will need 10GB of disk space, is there enough free space for the process to complete successfully?
From: Walter Roberson on 16 Jun 2010 20:19
Albert wrote:
> Walter Roberson <roberson(a)hushmail.com> wrote in message
> <hvbgth$6u9$1(a)canopus.cc.umanitoba.ca>...
>> There is no platform-independent answer for this, as some systems have
>> "infinite" disk storage (managed through techniques such as tape
>> migration.)
>>
>> The amount of space that is free _now_ is almost never the amount of
>> space that you can write to.
>>
>> If the question "can I produce a file this big?" then fopen() the file
>> for "a+", fseek() to the offset-1, fwrite() a byte and check to see if
>> the fwrite worked; if it did, then fseek() to the beginning of file
>> and go ahead and use the file. This will, however, not work if your
>> file system knows about "holes" and if your file system detects this
>> case as signaling that you want hole to be made.
>
> The questions is more: I want to run a process that will need 10GB of
> disk space, is there enough free space for the process to complete
> successfully?

What is the difference between what you are trying to do and my "If the
question is ..." technical discussion ? It is useless to ask _now_ about
whether 10GB total will be available _later_ on a shared filesystem. If
you want to know if you can write a file that size, write a file that
size (fseek + fwrite) and then you will have the space locked up (unless
the underlying filesystem supports "holes".)
From: Albert on 17 Jun 2010 18:49
I do not want to make a 10 GB file. The process will make 100s of files added up to a large size (20 some GB actually).

Of course, the original question is "how much free space is on the drive"? So to this end you would have me loop over creating larger files until the drive was full and I could not? Also if the drive only had 10 GB free and I used it, other process may break. I would be best to know how much was free prior to filling it up.

A further issue is that this drive has a backup system where deleted files are moved to the backup prior to the space being free. The delay in freeing space can be over a day. So if I fill the space using your technique I will still not be able to run the process as the drive would then be full even if it was not before I started.

But this trick would work for the simple question on a drive without this type of backup.
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