Hi,

On Sat, Dec 3, 2011 at 9:56 PM, Charles Darwin <[email protected]> wrote:
> Hi,
>
> I'm combining the Split File and File Family drivers in the following way:
> - Split File is applied in order to separate the data into two files
> (metadata and raw data, i.e. data.meta and data.raw)
>
> - then additionally, for the raw data storage the File Family driver is
> applied
>
> This results in having one metadata file (data.meta) and multiple raw data
> files according to the File Family member size setting (data0.raw, data1.raw
> etc.).
>
> For the most part this combination works as one would expect, but there is
> one circumstance in which it doesn't seem to work properly.
>
> Let's say that the file family member size is set 100 MB when creating the
> HDF5 file. If during the first write to this file the amount of data that
> ends up being written is more than 100 MB, for example 120 MB, then
> everything works as expected - the result is one data.meta file and two raw
> files; data0.raw which is 100 MB and data1.raw which is 20 MB, and appending
> even more data always results in *.raw files of 100MB (except for the last
> raw file which may not be full).
>
> However, if the first writing to this file is less than 100MB (less than the
> file family member size), for example 50 MB, and the file is closed, then
> this will create 2 files; data.meta and data0.raw of size 50 MB. This is all
> still as expected. If however, we then write more data to that file, then
> things work as if the file family member size setting was set to 50 MB
> rather than 100 MB, i.e. if we write 120 more MB to this file after closing
> it, this will result in data.meta, data0.raw of 50 MB, data1.raw of 50 MB,
> data2.raw 50 MB, and data3.raw of 20 MB.
>
> It's as if the setting for the file family member size is 50 MB rather than
> 100 MB, i.e. the file family member size becomes the size of the first raw
> file that is written, rather than the one that is specified in the creation
> properties.
>
> The HDF5 version is 1.8.7, operating system is Windows 7 64 bit.
>
> 1. Is the described file driver combination fully supported?

I would describe this as "Allowed behavior, but not explicitly
recommended and certainly not tested by us."  That said, I would
expect this setup to work correctly.

> 2. Is there a way to get around this behavior, so that the raw files end up
> respecting the file family member size creation setting, rather than
> inheriting the size of the first raw file after the first write session?

I'm not sure of a work-around that would fix your problem.

I've entered a bug report concerning this behavior since this sounds
like a bug in the driver.  I'm not sure how high of a priority it will
have since this is a more unusual way to use the virtual file drivers,
but I'll bring it up at our release planning meeting.

Thanks for reporting the issue!

Dana

> Thank you.
>
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