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any XLV experts?

Posted: Mon Feb 27, 2017 2:42 pm
by bamdad
hi everyone,

tonight i thought it would be a nice idea to do a mirrored (plexed) root so if one of my SCSI disks die i could boot off of the other one. so, having experience in linux and solaris LVM solutions, i dug up some documentation on how to do this..:

Code: Select all

xlv_make> vol xlv_root
xlv_root
xlv_make> data
xlv_root.data
xlv_make> ve -force /dev/dsk/dks0d1s0
xlv_root.data.0.0
xlv_make> end
Object specification completed
xlv_make> exit
Newly created objects will be written to disk.
Is this what you want?(yes)  yes
Invoking xlv_assemble

xlv_make> plex root_plex1
root_plex1
xlv_make> ve /dev/dsk/dks0d2s0
root_plex1.0
xlv_make> end
Object specification completed
xlv_make> exit
Newly created objects will be written to disk.


then, after trying to attach the root lv to the new plex i realised i messed up - this part needs a license but SGI didn't really make it obvious:

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xlv_mgr> attach plex root_plex1 xlv_root.data
invalid command option: plex
xlv_mgr> show config
Allocated subvol locks: 120     locks in use: 1
Plexing license: not present
Plexing support: present


so i deleted the plex on disk2 but now i'm wondering.. since the original /dev/dsk/dks0d1s0 is still there, can i detach the ve, delete the volume, undo the result of my bumbling around and go back to a non-xlv setup? without losing all my data? :)

prtvtoc shows the contents of disk1 stayed the same, aside from slice 0 changing type from 'xfs' to 'xlv':

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# prtvtoc /hw/rdisk/dks0d1s0
* /hw/rdisk/dks0d1s0 (bootfile "/unix")
*     512 bytes/sector
Partition  Type  Fs   Start: sec    Size: sec   Mount Directory
 0          xlv          8392704    134982034 
 1          raw             4096      8388608 
 8       volhdr                0         4096 
10       volume                0    143374738


any suggestions are highly appreciated.

thanks,
bamdad

Re: any XLV experts?

Posted: Mon Feb 27, 2017 3:14 pm
by Raion-Fox
Yeah you need a plexing license. I don't know if you can delete it or not. I would back up your data before you attempted it.

Re: any XLV experts?

Posted: Tue Feb 28, 2017 12:53 pm
by dexter1
Make sure to do an xfsdump/restore of your root disk before you delete the XLV labels.

I have ran a XLV mirror across two stripe sets, but never performed it on the boot disk. It probably needs some magic in the volume header, which is why you should back it up.

Re: any XLV experts?

Posted: Tue Feb 28, 2017 12:58 pm
by bamdad
update: since then i have sorted out the plexing problem, but before that, for the hell of it, did a proper backup (i did use xfsdump) and 'converted' root back to a 'normal' fs. i have seen no negative side effects, aside from that the header stayed xlv instead of xfs. the system booted just fine.

thanks for the advice. :)

i have also tested booting from the other plex, which worked fine. the only thing that's puzzling me now is that why does the system come up reporting the second VE as stale, even when we just booted right off of it.. after a while xlv_plexd sorts it out, but it's weird.