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Re: mirror boot disk without MirrorDisk/UX software

 
DIEGO_40
Occasional Contributor

mirror boot disk without MirrorDisk/UX software

Hi all,

I have a question:
Can I mirror boot disk and other not bootable disks without MirrorDisk/UX software?? Or is this indispensable on HP-UX for management mirroring??

Thanks
Ciao
6 REPLIES 6
Sundar_7
Honored Contributor

Re: mirror boot disk without MirrorDisk/UX software

I am sure this topic has been beaten to death number of times before if you ever search in the forum :-)

MirrorDisk/UX is sure has become one of the must-haves in any production data center server these days.

But there are ways to circumvent, again obviously with disadvantages.

you can use dd command to copy from one disk to an another and create a Mirror-kind copy.

Couple of things

1) At its best, it is just a static copy

2) If the primary disk breaks, system will not start using the mirror disk automatically.

above said, you can schedule a cron job that executes the following command

dd if=/dev/rdsk/ of=/dev/rdsk/ bs=1024k


Learn What to do ,How to do and more importantly When to do ?
Bill Hassell
Honored Contributor

Re: mirror boot disk without MirrorDisk/UX software

MirrorDisk/UX is not just a simple copy. It takes place at the driver level and ensures that each write is completed to the primary and to the mirror (or both mirrors if using 3way mirroring). If a write fails, the extent is marked stale, regardless of which disk (primary or secondary) is bad. Disks fail in very complex ways. Sometimes, just a few sectors are bad, other times, the electronics becomes very unstable. A simple disk copy will not create a bootable disk (due to SCSI addressing). The system will go down hard while you try to get the other disk ready for use.

MirrorDisk/UX is indeed indispensible for production and development systems. Just one disk failure will be much more costly in downtime than purchasing this product.


Bill Hassell, sysadmin
Steven E. Protter
Exalted Contributor

Re: mirror boot disk without MirrorDisk/UX software

Must have it. Period.

Now if you want to go vxvm, you can mirror the root disk without an upgrade.

I like LVM and mirror/ux better.

SEP
Steven E Protter
Owner of ISN Corporation
http://isnamerica.com
http://hpuxconsulting.com
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Sunil Sharma_1
Honored Contributor

Re: mirror boot disk without MirrorDisk/UX software

If you are using HP UX 11i. You can do root mirroring using VXVM. It's free with HP UX 11i.


Sunil
*** Dream as if you'll live forever. Live as if you'll die today ***
DIEGO_5
Occasional Advisor

Re: mirror boot disk without MirrorDisk/UX software

Ciao

Thanks for your support, I will try also vxvm

bye
Gerhard Roets
Esteemed Contributor

Re: mirror boot disk without MirrorDisk/UX software

Hi

Off course if you have bootable Fibre Channel Cards ... you can put your boot disks on an array ... Which you can Raid1 or Raid5.

Just a thought.

Regards
Gerhard