FW: Breaking hardware disk mirror to duplicate a system

Matt_Domsch@dell.com Matt_Domsch at dell.com
Thu Mar 20 13:07:26 CST 2003


Forwarding...

-----Original Message-----
From: colbey at dreamwerx.net [mailto:colbey at dreamwerx.net]
Sent: Tuesday, March 18, 2003 11:09 AM
To: linux-poweredge-admin at dell.com
Subject: RE: Breaking hardware disk mirror to duplicate a system



What gary is looking for is something like this.. a non-shutdown,
production snapshot backup..

I would think it's possible...   We used to have a box (not linux)
that had a 9 set/member raid 0 (stripe) .. Each raid 0 member was
a triple mirror..  27 drives in total..

It's design was to provide massive i/o.. and as well the system would
automatically disconnect the 3rd drive from each raid 1 set off..
and create a standalone 9 drive raid 0 stripe containing a snapshot of the
running system...  Dump the data to tape, and then re-integrate the disks
into the triple mirror config (The will just rebuild themselves over a
small period of time).

If I had the luxury of an extra poweredge/perc.. would be interesting to
try/look at..


On Tue, 18 Mar 2003, Mansell, Gary wrote:

> I do not have the luxury of being able to shut the server down so is there
a way to offline the mirror from linux before removing the drive?
>
>
> Gary Mansell
> Senior Technical Analyst
> IT Department
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Ricardo Consulting Engineers Ltd.          Direct Line:    01273 794485
> Bridge Works,                              Switchboard:    01273 455611
> Shoreham By Sea,                             Facsimile:    01273 794699
> West Sussex.                                  Internet: www.ricardo.com
> BN43 5FG                                  E-Mail: GRMansell at ricardo.com
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
>
> -----Original Message-----
> From: James Hall [mailto:jfhall8 at swbell.net]
> Sent: 17 March 2003 21:23
> To: Mansell, Gary
> Subject: RE: Breaking hardware disk mirror to duplicate a system
>
>
> This is not recommended to do.
>
> But, You should fail the drive by pulling it while the server is down
> and boot the server up. You should install a new drive and rebuild to it
> once it is failed.
>
> In the second machine that is identical hardware you would install the
> 2nd disk in the same slot. Then boot up. Then sync up with a new disk.
> That way you will have 2 healthy mirrors.
>
> -----Original Message-----
> From: linux-poweredge-admin at dell.com
> [mailto:linux-poweredge-admin at dell.com] On Behalf Of Mansell, Gary
> Sent: Monday, March 17, 2003 9:24 AM
> To: linux-poweredge at dell.com
> Subject: Breaking hardware disk mirror to duplicate a system
>
> As a means of protection, I would periodically like to break the mirror
> of my server and place it into an identical spare machine that I have as
> a "cold spare". I currently have a 2 PE2650's with identical mirrored
> system disks.
>
> This is the procedure that I envisage, please can someone confirm
> whether this is safe to do:
>
> 1) On the "cold spare" machine, at the Adaptec BIOS level, initialise
> both disks then remove them.
> 2) Pull the second drive from my production machine whist the machine is
> running.
> 3) Put the drive from 2) into my spare machine and boot from it.
> 4) put the two spare disks from 1) into each machine and wait for them
> to re-sync.
>
> Some questions come to mind:
>
> 1) Is this OK to do or are there command line tools that I should use to
> offline a disk before pulling it from a live running system? If so how
> do I do this?
> 2) I am presuming that initialising the disks (step 1) will ensure that
> the machine synchronises in the correct manner - ie, the machine will
> not try and mirror the initialised disk over the live system disk?
> 3) When the machine has rebuilt the degraded mirror, is the machine safe
> again or is there any settings that I need to change to tell the server
> that it is OK again. Do i need to reboot the server etc?
>
> Thanks in advance for any help
>
> Gary Mansell
> Senior Technical Analyst
> IT Department
> Ricardo Consulting Engineers Ltd
>
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