On Monday 14 June 2010, Neil Brown wrote: > On Sun, 13 Jun 2010 16:28:34 +0200 > > Bernd Schubert <bernd.schubert@xxxxxxxxxxx> wrote: > > On Friday 11 June 2010, Neil Brown wrote: > > > On Fri, 11 Jun 2010 00:31:57 -0400 > > > > > > "Graham Mitchell" <gmitch@xxxxxxxxxxx> wrote: > > > > Can you do this on a live array, or can it only be done (as the docs > > > > seem to suggest), with the create, build and grow options? > > > > > > As 'grow' can (and must) be used on a live array you're question > > > doesn't exactly make sense. > > > Yes: it can be done on a live array. > > > > While I have done this myself a couple of times, I still do not > > understand where it takes the disk space for the bitmap journal from? Is > > this space mdadm reserved for this purpose? > > Sort-of. > It uses space that the alignment requirements of the metadata assure us is > otherwise unused. > For v0.90, that is limited to 60K. For 1.x it is 3K. > With recent kernels it is possible for mdadm to tell the kernel where to > put the bitmap (rather than the kernel *knowing*) so mdadm could use other > space that was reserved when the array was created, but I haven't > implemented that in mdadm yet. Thanks a lot Neil! I added these information to the raid wiki https://raid.wiki.kernel.org/index.php/Bitmap#Used_disk_space_for_bitmaps Cheers, Bernd -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
