This has always been confusing to me. I have some new disk I need
to put into a large filesystem. The final filesystem is 137GB and
within this filesystem one of the files will range in size from
100GB -> 137GB, consuming the entire filesystem. I can create the
filesystem, but when I test the filesystem by creating a file that
is 100GB it fails at ~68GB.

What choices of NBPI and Allocation Group Size should I use for
this filesystem? I have tried several and the current is 16K
NBPI and 64M Allocation Group Size.

(AIX 5.2)

Mike

With JFS and default NBPI, your maximum filesystem size will
be 64 Gb (~68000 Mb). Any greater value for NBPI will allow you
to cross that limit.

NBPI & allocation group size depend on your filesytem usage, but
I would say that your choice is OK.

OBS: you could have avoided that trouble with JFS2 instead of JFS,
but there are other consideration with JFS2 that maybe not interest
you.

Mike a écrit:
>
> This has always been confusing to me. I have some new disk I need
> to put into a large filesystem. The final filesystem is 137GB and
> within this filesystem one of the files will range in size from
> 100GB -> 137GB, consuming the entire filesystem. I can create the
> filesystem, but when I test the filesystem by creating a file that
> is 100GB it fails at ~68GB.
>
> What choices of NBPI and Allocation Group Size should I use for
> this filesystem? I have tried several and the current is 16K
> NBPI and 64M Allocation Group Size.
>
> (AIX 5.2)
>
> Mike

In article <41019AF7.DED151D9@club-internet.fr>, Stephane Gassies wrote:
> With JFS and default NBPI, your maximum filesystem size will
> be 64 Gb (~68000 Mb). Any greater value for NBPI will allow you
> to cross that limit.
>
> NBPI & allocation group size depend on your filesytem usage, but
> I would say that your choice is OK.
>
> OBS: you could have avoided that trouble with JFS2 instead of JFS,
> but there are other consideration with JFS2 that maybe not interest
> you.
>
> Mike a écrit:
>>
>> This has always been confusing to me. I have some new disk I need
>> to put into a large filesystem. The final filesystem is 137GB and
>> within this filesystem one of the files will range in size from
>> 100GB -> 137GB, consuming the entire filesystem. I can create the
>> filesystem, but when I test the filesystem by creating a file that
>> is 100GB it fails at ~68GB.
>>
>> What choices of NBPI and Allocation Group Size should I use for
>> this filesystem? I have tried several and the current is 16K
>> NBPI and 64M Allocation Group Size.
>>
>> (AIX 5.2)
>>
>> Mike

It was the 64GB limit causing the problem. Next week we will create
the filesystem as JFS2.

Mike

Mike wrote:

> This has always been confusing to me. I have some new disk I need
> to put into a large filesystem. The final filesystem is 137GB and
> within this filesystem one of the files will range in size from
> 100GB -> 137GB, consuming the entire filesystem. I can create the
> filesystem, but when I test the filesystem by creating a file that
> is 100GB it fails at ~68GB.

How are you trying to create the file? What error code is returned?
Please be exact.

> What choices of NBPI and Allocation Group Size should I use for
> this filesystem? I have tried several and the current is 16K
> NBPI and 64M Allocation Group Size.

If the filesystem is 137GB, then choosing 16kNBPI will allocate
137*1024*1024*1024/16*1024 inodes. That is, about 9 million. That may
sound like a lot but it depends on how many files you are expecting in
the filesystem.

The allocation group size basically defines the disc blocks to be
allocated as follows from block zero:

<some inodes><data blocks><some inodes><data blocks> and so on.

The idea is that inodes are allocated near-ish the data blocks they
relate to. Shouldn't matter much for you big file.

Check out
http://www.unet.univie.ac.at/aix/aix...size_under.htm.