On Wednesday May 13, eyal@xxxxxxxxxxxxxx wrote: > If I have a live raid and want to enable bitmap then I do > mdadm --grow /dev/md0 --bitmap=internal > Does this bitmap use space in the already present header? If so then > does this mean that the headers have enough reserve for this? Why > not always use the bitmap then? 1/ Yes. 2/ Yes. 3/ because there are other reasons for not wanting a bitmap. Using a write-intent bitmap can cause a reduction in throughput. It is conceivable that having a bitmap should be the default, but it should definitely be options. In fact, ever array does has a default bitmap. However that bitmap contains exactly one bit, and it cover the whole array. It is the clean/active flag. Defaulting to a few more bits is possibly a good idea... > > If it carves extra space from the device which already has data > (e.g. a fs) then surely this will be problematic. Yes. It surely would be. NeilBrown -- 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
