On Fri, 7 Mar 2025 14:42:24 -0600 Roger Heflin <rogerheflin@xxxxxxxxx> wrote: > I put an external bitmap on a raid1 SSD and that seemed to speed up my > writes. I am not sure if external bitmaps will continue to be > supported as I have seen notes that I don't exactly understand for > external bitmaps, and I have to reapply the external bitmap on each > reboot for my arrays which has some data loss risks in a crash case > with a dirty bitmap. > > This is the command I used to set it up. > mdadm --grow --force --bitmap=/mdraid-bitmaps/md15-bitmap.img /dev/md15 In this case the result cited seems to have shown the bitmap is not the issue. I remember seeing patches or talks to remove external bitmap support, too. In my experience the internal bitmap with a large enough chunk size does not slow down the write speed that much. Try a chunk size of 256M. Not sure how high it's worth going before the benefits diminish. -- With respect, Roman
