Re: switching root fs '/' to boot from RAID1 with grub

2007-11-03 Thread Bill Davidsen
H. Peter Anvin wrote: Bill Davidsen wrote: Depends how "bad" the drive is. Just to align the thread on this - If the boot sector is bad - the bios on newer boxes will skip to the next one. But if it is "good", and you boot into garbage - - could be Windows.. does it crash? Right, if the

Re: switching root fs '/' to boot from RAID1 with grub

2007-11-03 Thread H. Peter Anvin
Bill Davidsen wrote: Depends how "bad" the drive is. Just to align the thread on this - If the boot sector is bad - the bios on newer boxes will skip to the next one. But if it is "good", and you boot into garbage - - could be Windows.. does it crash? Right, if the drive is dead almost e

Re: switching root fs '/' to boot from RAID1 with grub

2007-11-03 Thread Bill Davidsen
berk walker wrote: H. Peter Anvin wrote: Doug Ledford wrote: device /dev/sda (hd0) root (hd0,0) install --stage2=/boot/grub/stage2 /boot/grub/stage1 (hd0) /boot/grub/e2fs_stage1_5 p /boot/grub/stage2 /boot/grub/menu.lst device /dev/hdc (hd0) root (hd0,0) install --stage2=/boot/grub/stage2 /b

Re: stride / stripe alignment on LVM ?

2007-11-03 Thread Doug Ledford
On Sat, 2007-11-03 at 21:21 +0100, Janek Kozicki wrote: > > If you run mdadm -D /dev/md1 it will tell you the data offset > > (in sectors IIRC). > > Uh, I don't see it: Sorry, it's part of mdadm -E instead: [EMAIL PROTECTED] ~]# mdadm -E /dev/sdc1 /dev/sdc1: Magic : a92b4efc V

Re: stride / stripe alignment on LVM ?

2007-11-03 Thread Janek Kozicki
Doug Ledford said: (by the date of Sat, 03 Nov 2007 14:40:48 -0400) > so you really only need to align the > lvm superblock so that data starts at 128K offset into the raid array. Sorry, I thought that it will be easier to figure this out experimentally - put LVM here or there, write 128k of

Re: stride / stripe alignment on LVM ?

2007-11-03 Thread Doug Ledford
On Fri, 2007-11-02 at 23:16 +0100, Janek Kozicki wrote: > Bill Davidsen said: (by the date of Fri, 02 Nov 2007 09:01:05 -0400) > > > So I would expect this to make a very large performance difference, so > > even if it work it would do so slowly. > > I was trying to find out the stripe layou

Re: [RFC PATCH 2.6.23.1] md: add dm-raid1 read balancing

2007-11-03 Thread Rik van Riel
On Sat, 03 Nov 2007 20:08:42 +1000 Konstantin Sharlaimov <[EMAIL PROTECTED]> wrote: > This patch adds RAID1 read balancing to device mapper. A read > operation that is close (in terms of sectors) to a previous read or > write goes to the same mirror. > > Signed-off-by: Konstantin Sharlaimov <[EMA

Re: Superblocks

2007-11-03 Thread Bill Davidsen
Greg Cormier wrote: Any reason 0.9 is the default? Should I be worried about using 1.0 superblocks? And can I "upgrade" my array from 0.9 to 1.0 superblocks? Do understand that Neil may have other reasons... but mainly the 0.9 format is the default because it is most widely supported and al

[RFC PATCH 2.6.23.1] md: add dm-raid1 read balancing

2007-11-03 Thread Konstantin Sharlaimov
This patch adds RAID1 read balancing to device mapper. A read operation that is close (in terms of sectors) to a previous read or write goes to the same mirror. Signed-off-by: Konstantin Sharlaimov <[EMAIL PROTECTED]> --- Please give it a try, it works for me, yet my results might be system-speci