[SunHELP] Moving a DiskSuite array

[Hichael Morton]

if moving the md.cf file entries to the machine b doesn't work, you 
should be able to recreate the layout on the new machine.  if you cause 
disksuite to initialze the disks, you will lose the data.

we lost our disk suite md setup after a power outage.  we rebuilt the 
partitions from the md.cf (saved on another machine and a hard copy in 
the machine's file) and recover everything.  thankfully, the partition 
information was intact in format and format information could be used 
also to rebuild the md configuration.  (we use the same slices for data 
and the same slices of metadbs  on each disk we place under disksuite 
control.)

swap holds a lot of stuff that is used by the os to control the system. 
  if swap is striped and a stripe dies, the os will die also.  the os 
will not reboot (properly) because the swap in the vfstab will not 
exist.  the kernel in solaris 8 does some extremely sophisticated things 
and a lot of the tools we now use are based on information in swap. 
swap is very important these days.

the sysadmin courses have information on this as should the solaris 
system administration guides.

on a test machine, create swap on a striped volume and then test it. 
pull out a drive in the swap striped volume and see what happens. record 
you findings and put it in your summary.



Phil Stracchino wrote:
> OK, folks, here's a couple of questions for y'all.
> 
> 
> I have machine A, an Ultra1 running Solaris8, with an attached 711 disk
> pack stuffed full of 9G Cheetahs with ...  um, lemmesee ...   five
> stripes across them.  I also have machine B, an Ultra30 running
> Solaris9.  I would like to detach the 711 from machine A and attach it
> to machine B.
> 
> Can I do this non-destructively by copying the appropriate lines
> from machine A's /etc/lvm/md.cf to machine B?  If this won't work, is
> there some other way to move the array non-destruvtively?  Or must I
> recreate all the stripes from scratch on machine B after moving the 711,
> then restore the data from tape?
> 
> 
> On a related subject:  In Linux, if you create two swap partitions of
> the same size and assign them the same swap priority, the kernel is smart
> enough to automatically (and silently) stripe them for faster swap
> performance.  Solaris, I know, does not do so.  Can swap on a Solaris
> machine be placed on a stripe metadevice without ill effects?  When I've
> tried it, I've seen odd error messages about overlapping swap areas, but
> it seemed to work, so I don't know whether this is a serious error or
> just a case of the kernel running into something it didn't expect.
> 
> (As a side note, when I've discussed this subject elsewhere in the past,
> people have said that having swap on a striped device is dangerous if
> you lose a disk, but it seems to me that if you lose a disk that has
> active swap in use on it, you're in a world of hurt regardless of
> whether the swap was striped or not.  So this seems like a specious
> argument.  If someone can explain to me why it isn't, please elucidate.)