Disk mirroring

[Prathamesh_1]

How disk mirroring can be done in hp-unix rp8420 mid range server and why disk mirroring is so important

[Pete Randall · Accepted solution]

There are two forms of disk mirroring. Hardware mirroring is accomplished using an array designed for this purpose. Software mirroring is achieved using the LVM product MirrorDisk/UX, which has to be purchased.

The importance of mirroring depends on your needs for availability. A well designed mirrored environment can survive hardware failures and continue to run, right on through the repair and replacement of failed components. If uptime is not critical, then the expense of mirroring is not justified. If it is critical, then the expense of downtime compels some type of mirroring.

By the way, hardware mirroring is typically the faster of the two. Therefore, it is common to use software mirroring for the OS volumes and to place the data volumes onto an array where mirroring will be faster.


Pete

[freddy_21]

Hello,


Requerement for mirroring:
You need two disk with same size.
You need Software mirroring

I think you have mid range server, and i think this is important server for your production

Could you imagine what happen when your OS disk failed. Your production will be down until your enginner come and fix it ( maybe 4-5 hours with ignite tape and waiting your enginner come to your site). with the mirroring you just boot from mirror disk ( maybe 1 hours only).

This is will improve your High availibility from your server.


Thanks
Freddy

[susee_sundar]

Hi Prathamesh.,

If u r going for Mirroring Root system disk in LVM....Here is the cook book Which i hope will help you....

#lvlnboot -v
<< will display the current system Boot disk >>

<< If u want to Mirror c2t5d0 disk to the system disk >>

#pvcreate -B /dev/rdsk/c2t5d0
#mkboot -a "hpux" /dev/rdsk/c2t5d0
#vgextend /dev/vg00 /dev/dsk/c2t5d0
#vgdisplay -v /dev/vg00

<< to display the current logical volume structure in VG00 >>

#lvextend -m 1 /dev/vg00/lvol1 /dev/dsk/c2t5d0
#lvextend -m 1 /dev/vg00/lvol2 /dev/dsk/c2t5d0

<< Extend in the same way for all volumes >>
#lvlnboot -R
<< to reconfigure the boot Devices >>
#lvlnboot -v
<>
#setboot -a << HW path of the disk >>
-->to set it as alternate boot
#vi /stand/bootconf
l /dev/dsk/c2t5d0
<< put an entry in the file >>

Thats it now you configured an alternate boot disk for your system..

In case of your system diak failure the system will start booting from the alternate disk..


regards
Surya.....

[Alzhy]

Mirroring is done depending on which volume manager you are using. HP-UX supports 2 volume managers - LVM and VxVM and trhe approach to mirroring is quite similar and fully documented in many HP documents and posts in this forum.

Why mirror? For safety and redundancy (so if you loose one disk, you do not loose data). You may be aware that most of the "good" things in life - including parts of your anatomy - come in 2's. You can think of mirroring using the same analogy.


Hope this helps.