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problem creating mirrored disk

Posted on 2009-06-29
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i am trying to create a mirrored disk and have been using instructions in article id:  302969.  i have a 36 gig scsi drive (0) in a dell 1600sc, running windows 2000 server.  i bought an identical drive for the mirror (1).  the computer recognizes the second drive.  i made both of them dynamic drives.  i deleted the partition of the second drive (1) so it shows as being 34.22 gig unallocated space.  but per instructions in article, when i right click on current drive (0) i do not get an option to 'add mirror.'  What am i doing wrong?  thanks.  dan
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Question by:m3surveys
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by:mds-cos
ID: 24740366
Did you reboot after making both drives dynamic?
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by:m3surveys
ID: 24740511
yes, i have re-booted a couple times.  dan
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by:mds-cos
ID: 24740981
I don't do software mirroring, so it has been a long time.  But something is nagging me that you should select both the current partition and the unallocated space before you right-click.
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by:m3surveys
ID: 24741378
i'm not sure i understand why you would be making suggestions in an area (mirroring) with which you are not familiar.  i'm trying to mirror my main data base engine (sql server) and really cannot afford to wipe out this hard disk.  dan
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by:m3surveys
ID: 24741513
ok, was able to create mirror for c and d drives on main disk (by doing the mirroring by partition rather than for whole disk).  i see that i have a 55mb partition on original disk that says, 'healthy (eisa configuration)."  it will not allow me to mirror this partition--but do i need to?  thanks.  dan
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by:mds-cos
ID: 24741537
I did not say I'm not familiar with it, I just said I don't do it so it's been awhile (last time I set up software mirroring for somebody was about a year ago).

Understand that my "I don't do it" is an engineering statement that implies software mirroring is bad, not an experience statement saying I am not intimately familiar with the task.  I have set it up, and done troubleshooting when it broke many, many, many times.  I have done it often enough that whenever I am forced to set up software mirroring I sit down and do it correctly right away without even thinking about what I'm doing.  Just kind of happens automatically after so many years.  But my jumping up and down on my soapbox recommendation is always "quit using software mirroring and start using hardware mirroring".  Basically any server that I spec out will use hardware mirroring.

Now that you tell me you are setting up SQL server, I am really going to jump up on that hardware RAID soap-box.  Software mirroring is not as reliable nor does it offer the same performance as a good hardware RAID card.  I would NEVER IN A MILLION YEARS set up one of my critical SQL servers on software RAID.  It is asking for trouble.
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by:mds-cos
ID: 24741579
This is a bit outside the scope of your question, but how big is this SQL server?  The reason I'm asking is because from the info in your question it sounds like you are planning on setting it up on the same spindle as your OS.

Best practices for a database server is to separate the database from the OS and other apps (bigger database servers begin separating out logs and multiple databases as well).  If the database is small you won't have any issues.  But if the database is of any appreciable size you will want to consider adding two more disks as (hardware) RAID1 or three as (hardware) RAID5 specifically for your database.

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by:mds-cos
ID: 24741609
Oh, yes!  You don't ever mirror the whole disk with Windows software mirroring -- you always mirror specific partitions.  I did not realize that you were attempting to click on the disk itself rather than the partition.

The eisa partition is a utility partition that is not required by the OS.  It will contain hardware specific diagnostic, configuration, and other such utilities.  When I do software mirroring I like to create this partition on my drives using the manufacturer supplied disks *before* I set up the mirror -- but this is strictly my preference because I'm anal and like to have the utility partition on any drive I might end up needing to use in the future.
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by:m3surveys
ID: 24741767
mds-cos:  thanks for the closer analysis and i understand you have a lot of experience with these issues. i also understand that a software solution is not the best.  here's more about my situation and what i am trying to achieve.  at one time, i had several employees and a multi-seat system of processing data so i am not creating a new sql database--it is already installed (os is on c drive and sql is on d drive).  now it's just me and i am trying to set a back up system with multiple redundancies.  i have two 1600sc's that are mission critical--one is the sql server and the other is the network server.  in extreme situation--complete meltdown of server--i want to be up and running within a couple hours.  to this end, i bought a couple extra 1600sc's and one back up plan is to take the sql mirrored drive and boot up that machine.  as a mirror, it should be ready to go (i'm backing up the data base regularly on another pc, so i can just restore the data base).  i'm also planning on creating an image of the disk so that would be another option to get the system back up.
ok, sounds like me are on the same page--what issue is still open?  as far as i can tell, it's just this extra eisa partition.  it sounds like i don't need to worry about this.  
i guess the other issue is just trying to boot up another computer with the mirrored disk.  i've read several times that i would need to edit the boot.ini file.  any tips on what to edit in that file to get computer to see mirrored drive on another machine as the primary drive?  thanks for your help.  dan
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by:mds-cos
ID: 24741880
OK, I think I understand what you are doing.  Will you be leaving the mirror disk in place, or pulling it out right away for your cold standby?  If you are pulling it out, remember to delete the "missing" disk from your mirror set as clean up.

Nothing else for your mirror -- you are done besides testing.  Based on what you are doing, I certainly would not worry about putting the utility partition on.

Editing the boot.ini allows you to boot from either disk in the mirror.  Now Windows updates the boot.ini automatically when a software mirror is established, but based on the zone you posted in your are running an older version.  The instructions you are following should discuss editing the boot.ini file, and how to figure out the ARC path.  If not, here is a link to help figure out the correct ARC for your system (http://support.microsoft.com/kb/102873).  But in your case it sounds like you don't plan on booting the "live" server off the mirrored drive, but rather being able to plug it into the first slot of your standby system and boot up.  If the two systems are identical, ARC paths should match so you should not have to edit the boot.ini.  But you need to test this.  If one system has SCSI and the other IDE, ARC path will be different.  You will know if the ARC path is wrong because it will start to boot, then fail to load Windows.

Something to watch for if you are leaving the mirror disk in place is that software mirroring often breaks for no apparent reason (of course there is a reason, but drilling down to it can be difficult....I had one customer with minor intermittent SCSI issues that broke their software mirroring every couple of months).  When it breaks, the mirror drive may or may not be viable.  This means you need to monitor to be sure all is working right.  If the mirror quits working you will need to re-establish it.

As you are already aware, corruption of the OS or SQL database will not be protected by the mirror.  Seems that your other backups have you well covered for this.


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mds-cos earned 125 total points
ID: 24741883
P.S.  Be sure the mirror is fully synchronized before you pull the drive ;-)
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