Re: Disk Mirroring help

In article <m24poatssb.fsf@xxxxxxxxxxxxxxx>,
Frank Cusack <fcusack@xxxxxxxxxxx> wrote:
On 24 Mar 2007 09:35:43 -0700 "learner" <Zabaloch@xxxxxxxxx> wrote:
Hey gurus,
I want to mirror the disks running Sun Solaris 8. The problem is that
I never assigned slices for SDS at the time of OS installation. Now
the OS is running and I want to run fdisk or some other utilities to
define partitions in order to install and mirror the disks. Any
suggestions on how to partition slices while the OS is running?
Unfortunately, I do not have boot CD for Sun Solaris 8 since the copy
I made is not working for some absurd reason.

Can't be done unless you can unmount a slice and lose the data on it.

You're making the assumption that there are no slices free. If there
are available slices for use, then one needn't lose any data.

But since you are mirroring, you must have 2 disks, and all of the
data must be able to fit on only one disk, so if the data isn't
already on just one disk, migrate it over, then you can create a
metadata slice and data slices on the other disk, move all your data
over there, then finally attach the first disk as a mirror.

That's kind of labor intensive and possibly unnecessary (if there are
still unallocated slices). Instead of all that data moving business,
one can simply steal space from the swap partition and assign those
blocks to an available slice. Basically:

- unmount the swap device (swap -d <SwapDevice>)
- use the format tool:
- reduce the size of the swap partition by a couple cylinders
- allocate those cylinders to an available slice
- remount the swap device (swap -a <SwapDevice>)

Once the above is done, follow the procedures for mirroring root as
normal.

On a side note, if you're only using SDS for root disk mirroring and
only have metadbs on two disks, you might want to add the following
to your /etc/system (at least this used to be needed):

set md:mirrored_root_flag=1

This way, if you have to reboot and one member of the mirrored pair
is dead, you can still reboot without having to ass about with
deleting the references to the failed disk's metadb copies.
--

"You can only be -so- accurate with a claw-hammer." --me
.

Relevant Pages

  • Re: Disk Suite question
    ... Used prtvtoc and fmthard to mimic the first disk. ... >> Which I then can use metainit to create a mirror. ... > on slices that hold no data". ... to then try and create the databases using metadb. ...
    (comp.unix.solaris)
  • Re: fsck a disk hosting several SVM submirrors
    ... submirror offline, fsck the given disk slice, then re-attach it to its ... mirror, all without unmounting the FS which the mirror hosts. ... system into single user mode and check the slices on the problem disk. ...
    (comp.unix.solaris)
  • Re: fsck a disk hosting several SVM submirrors
    ... the FSs on the disk. ... submirror offline, fsck the given disk slice, then re-attach it to its ... mirror, all without unmounting the FS which the mirror hosts. ... slices on the bad disk, and booting back into runlevel 3, must I ...
    (comp.unix.solaris)
  • Re: Cleanly break SVM root mirror before some tests
    ... Ian wrote: ... >> the disk and do my tests. ... Detach the slices and do a test ... metasync -r line commented out so that the mirror resync wouldnt start ...
    (comp.unix.solaris)
  • Re: How to safely merge two slices on harddisk?
    ... The disk slices are as follows: ... all the information from /mnt into some new tree in /usr/ports. ... Having done that partition /dev/ad1s1g becomes free and you ...
    (freebsd-questions)