[lkml]   [2007]   [Jun]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: limits on raid
On Sun, 17 Jun 2007, Wakko Warner wrote:

> dean gaudet wrote:
> > On Sat, 16 Jun 2007, Wakko Warner wrote:
> >
> > > When I've had an unclean shutdown on one of my systems (10x 50gb raid5) it's
> > > always slowed the system down when booting up. Quite significantly I must
> > > say. I wait until I can login and change the rebuild max speed to slow it
> > > down while I'm using it. But that is another thing.
> >
> > i use an external write-intent bitmap on a raid1 to avoid this... you
> > could use internal bitmap but that slows down i/o too much for my tastes.
> > i also use an external xfs journal for the same reason. 2 disk raid1 for
> > root/journal/bitmap, N disk raid5 for bulk storage. no spindles in
> > common.
> I must remember this if I have to rebuild the array. Although I'm
> considering moving to a hardware raid solution when I upgrade my storage.

you can do it without a rebuild -- that's in fact how i did it the first

to add an external bitmap:

mdadm --grow --bitmap /bitmapfile /dev/mdX

plus add "bitmap=/bitmapfile" to mdadm.conf... as in:

ARRAY /dev/md4 bitmap=/bitmap.md4 UUID=dbc3be0b:b5853930:a02e038c:13ba8cdc

you can also easily move an ext3 journal to an external journal with
tune2fs (see man page).

if you use XFS it's a bit more of a challenge to convert from internal to
external, but see this thread:

i found that i had to do "sb 1", "sb 2", ..., "sb N" for all sb rather
than just the "sb 0" that email instructed me to do.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2007-06-17 19:33    [W:0.117 / U:6.936 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site