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raw devices - moving to new disk.

Deepak Seth_1
Regular Advisor

raw devices - moving to new disk.

I have couple of raw devices which are used for my sybase database. Iam moving the data from exisitng raw devices to new raw devices on a different disks.

Is the following steps ok.
1. create raw devices on new disk of the same size as on the old/existing disks.
2, shutdown the sybase.
3. dd if=/dev/vg??/rlvol?? of=/dev/vg??/rvol?? bs=64k - for each of raw devices.
4. start the sybase database - i think i need to change the mappng some where is
sybase - so its points to correct/new device,



6 REPLIES
Andreas Voss
Honored Contributor

Re: raw devices - moving to new disk.

Hi,

you procedure seems ok to me.

Regards
Lasse Knudsen
Esteemed Contributor

Re: raw devices - moving to new disk.

Looks fine - just make sure that your lv's are exactly the same size. (But I guess you already have that one figured out)
In a world without fences - who needs Gates ?
Richard Quinn_1
Occasional Visitor

Re: raw devices - moving to new disk.

You can do it that way but you will need to update your master..sysdevices table in Sybase so that it now points to the new devices.
Another way of achieving this (and keeping the database server online) would be to use the Sybase command 'DISK MIRROR' to mirror to the new device and then break the mirror using 'DISK UNMIRROR' and setting the SIDE to "SECONDARY".
hope this helps.
"Though this be madness, yet there is method in 't." !!
Carol Garrett
Trusted Contributor

Re: raw devices - moving to new disk.


If you use dd you have to have your db down, instead add the new disks to the same VG as the existing ones and use pvmove to move your raw lvols to the new disks. Using this method your db can stay up and running!
Richard Quinn_1
Occasional Visitor

Re: raw devices - moving to new disk.

As far as I know, the VG needs to be deactivated before you do a pvmove and you'll have to bring down rhe db server for that.
"Though this be madness, yet there is method in 't." !!
Carol Garrett
Trusted Contributor

Re: raw devices - moving to new disk.

No, you dont need to deactivate a VG in order to do a pvmove. You can do it online - thats the whole point of this command.