Re: [Qemu-devel] hd-geo-test creates 4GB files on FSes that don't support sparse images, doesn't delete them on error

[John Snow <jsnow@redhat.com>]

On 08/27/2015 11:29 AM, Eric Blake wrote:
> On 08/27/2015 09:17 AM, Peter Maydell wrote:
>> I've noticed recently that tests/hd-geo-test.c creates test disk
>> images which are 4GB in size, which is a problem if the filesystem
>> on the host doesn't support sparse files. In particular, OSX's HFS+
>> doesn't have sparse file support, and Windows probably doesn't either.
> 
> Windows NTFS supports sparse files (minimum hole size of 64k), but it
> can be a pain to set up, and while it saves disk space, it may actually
> slow your program down.
> 
> [At one point cygwin created sparse files on windows by default, but
> because it was demonstrated to hurt performance in dealing with sparse
> files, because Windows doesn't handle sparse files efficiently, the
> cygwin defaults were switched so that it now requires an explicit opt-in
> mount option before even attempting sparse files]
> 
>> Worse, if the test fails an assertion somewhere the test doesn't
>> clean up after itself and leaves a 4GB file lying around in /tmp/.
>>
>> It would be nice if we could skip these tests on filesystems that
>> don't have sparse file support...
> 
> Or even where sparse files are supported but not default.
> 

Does this test *require* the raw format?

Use tests/libqos/libqos.c mkqcow2 instead. I'll send a patch.

--js