[Libvir] PATCH: 12/16: logical volume backend

Jim Meyering jim at meyering.net
Tue Feb 19 15:13:32 UTC 2008


"Daniel P. Berrange" <berrange at redhat.com> wrote:
...
>> > +    for (i = 0 ; i < pool->def->source.ndevice ; i++) {
>> > +        int fd;
>> > +        char zeros[512];
>> > +        memset(zeros, 0, sizeof(zeros));
...
>>   is it really 512 or the block size on the device used ? But 512 is
>> probably sufficient for LVM to consider it cleared, just wondering ...
>
> The 'pvcreate' man page explicitly says the first sector
>
> <quote>
>    For whole disk devices only the partition table must be erased,
>    which will effectively destroy all data on that disk.  This can
>    be done by zeroing the  first  sector with:
>
>        dd if=/dev/zero of=PhysicalVolume bs=512 count=1
> </quote>
>
> So 512 is fine for MSDOS partition tables at least.

How about giving the constant a name?
That'd make it more readable.

#define SECTOR_SIZE 512

--
Jim, who has spent far too much time dealing with hard-coded
literal array sizes like that in parted, when I made
parts of it work with larger-than-512-byte sectors.




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