Mirroring raw Sybase devices

[gevans]

I am currently using Sybase mirroring to mirror our raw device based database, (really bad idea I have found out). I want to convert to HP-UX mirroring if possible. Does HP-UX mirroring effectively mirror raw LVM devices?
I can't seem to find any documentation that explicitely says it does or does not.

[Peter Nikitka]

Hi,

of course HP-UX supports mirroring at the LVM level. You need the product 'MirrorDisk/UX' (license is NOT free - codeword required) to get what you want.
To check, if that product is already installed, look at the output of
swinstall LVM

If you see something like
LVM.LVM_MIRROR

you should look at the man page of 'lvcreate'.

mfG Peter

[Bill Hassell]

Mirroring has no relationship to filesystems -- it doesn't know anything about the use of a logical volume, so yes, you can mirror any lvol, whether it has a filesystem, is a swap area or contains raw data for Sybase (or Oracle, Informix, whatever). If you don't have mirroring installed, your entire system is at risk. Once you have mirroring installed, you extend each logical volume with the -m option. The lvol will be synced and from that point on, mirroring is automatic.

[Steven E. Protter]

Shalom,

You don't mirror filesystems, you mirror logical volumes.

You use mirror/ux the same way you would on a "filesystem"

One of my colleagues, actually my boss here has a little trick to make raw disk visible. He softlinks to it.

That does not change the mirror process, but it does make that consultant who is poking around less likely to destory the raw disk area, because there is something visble out there for all to see.

SEP

[Raj D.]

Gevans,

Mirrored disk operations require the installation of the optional HP MirrorDisk/UX software, which is not included in the standard HP-UX operating system.

lvcreate or lvextend can be used to mirror the logical volume. with -m option to specify the mirror_copy.

mirror_copy :Set the number of mirror copies allocated for each logical extent. A mirror copy contains the same data as the original.

mirror_copies can be 1 or 2.

Example:
To mirror a logical volume (lvol1 may be mounted as any filesystem say /syb1 )to a particular physical volume:

# lvextend -m 1 /dev/vg01/lvol1 /dev/dsk/c1t1d0

For further details:
http://docs.hp.com/en/B2355-90129/lvcreate.1M.html

Cheers,
Raj.

[gevans]

Thanks everyone who responded. I have acquired the needed mirroring and converted all to HP-UX mirroring. I am sleeping better.

[Raj D.]

Gevans,

Nice to know that you are sleeping well, and mirroring helping a lot,

Great!! now the last part you need to asign points to the above who all tried to help you. and to close the thread(optional).


Cheers,
Raj.

[gevans]

Thanks everyone for your help.

[Peter Nikitka]

Hi,

help reference for point assignments:

http://forums1.itrc.hp.com/service/forums/helptips.do?#33

mfG Peter