On Tuesday May 15, mangoo@xxxxxxxx wrote: > Neil Brown schrieb: > > (...) > > > An external bitmap means that if the link goes down, it keeps track of > > which blocks are in sync and which aren't, and when the link comes > > back up you re-add the missing device and the rebuild continues where > > it left off. > > > mdadm --build /dev/md22 --level=1 --bitmap=/root/mybitmap \ > > --write-behind --raid-disks=2 /dev/localdevice --write-mostly /dev/remotedevice > > One more question - is there a way to estimate the size of the bitmap > file? Does it depend on the size of the array? > > What bitmap file size can I expect for a 600 GB array? Due to internal implementation details, mdadm limits the size of the bitmap to 2^20 bits. So the file will be 100K +/- 50%. That will lead to about 1Meg per bit. If you have a failure, this might mean you end up re-copying several megabytes more than you really need to, but that should add up to less than one second. 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
