Breaking Mirror - What will happen to data please? 2

[johnnybb2000]

Hi,

Am trying to Ghost a RAID1 configured disk. I have tried to straight run Ghost.exe, however it gives an error before it even begins. I have looked at the Symantec website, and everything points to the fact that Ghost does not support RAID configured disks. I have called Compaq Warrantee line and they cannot garauntee anything!

Basically, I want to break a mirror set, and Ghost the single disk, which I believe will work, then reestablish the mirror.... everybody happy!! Unfortunately I have never "Broken a Mirror" within the Compaq Array Configuration Utility, and cannot be sure the data will be safe. I can break it two ways; from booting into the SmartStart CD and running the Compaq Array Configuration Utility or run the Compaq Array Configuration Utility within the OS (NT).

Can anyone be totally sure the data will be safe when I break the mirror?

Can anyone help?

TIA,

John

 

[Beaghler]

Need some more info- What OS, what type of drives, controller, etc.

What are you trying to accomplish with the image? There may be a simpler solution. Making a mirror go away is a lot of trouble.

 

[johnnybb2000]

What OS - NT4 SP6a
What type of drives - 2 x 4.3GB SCSI WU
Controller - Symbios Logic (Compaq Spec, can get more details if required, but not on site with server today).
It also has a second RAID controller controlling a Storage array of 6 9.1 UW2 (5 RAID5 + 1 hot Spare) - disconnected for "safety".

What are you trying to accomplish with the image?
*Trying to Ghost off the OS and App configuration as a Baseline for an Integration process. Then we have to build to new baseline, with the option to roll back to the image if necessary.

There may be a simpler solution - we only use Symantec GHOST available for this solution i.e. no Tape backup available.

Making a mirror go away is a lot of trouble - Interesting? Why, if you have time to explain this statement?

I have been dealing with Mirrored drives in the my last job with no problems however it was in an operational environment as opposed to Integration environment, therefore only have to swap dead disks of a mirror - no problem, or build them from scratch. NB: Using Tape B-U and B-U Exec to backup and restore.

Thank you very much for your reply, appreciated.

John

 

[Beaghler]

I've not been in the position of having to break a mirror at the system level. I've done at the OS level (NetWare)without any problem. The array configuration utility is the only way I know, and like you, am not 100% comfortable with the process. It's not real pretty as far as I know. My statement about a lot of trouble is probably not really accurate, more properly, I should have said time consuming. We quit using Mirroring in this shop several years ago, and are just now looking at it again for use in conjunction with SAN. We've found RAID 5 to be quite satisfactory.

Since what you want to do is just come up with a new baseline, why not just pull the drives and replace them. You'll have the old data in a safe place, and can start completely fresh. If it doesn't work out, replace the drives and you're back in business. We do that on our RAID 5 servers occasionally, and it works a treat, as long as the drives go back into the same slot as they came out of.

 

[johnnybb2000]

Thanks again for the info, marked as Helpful etc. What were you using as your front end for the Netware you talk about? NT? Cos if you were, then we are cooking on gas. I can do it at OS level; simply flash up the Compaq Array Config Utility, Modify, drop Disk1 back onto the Array controller, and as far as I know - or logic dictates - this should break the mirror. One would assume that a shutdown, remove the (literally!) redundant disk, reboot, everything fine??? I just can't see the data being damaged, cos it simply would be ridiculous.... Wouldn't it???

Well that is my theory however, the only doubt that was put in my mind was by my boss, who said that he wasn't sure, therefore putting doubt in my mind, and of course making me responsible if I try it.... Bit of politics, sorry.

Your idea with the secondary DISKS is one that we have talked about in the past. It would be better and safer, enabling one to have an image waiting on the spare disks while we wait for the developers to hand the test rig back to us. Unfortunately, my other task with the process is to produce a document on how to Ghost off a server with RAID1, breaking the mirror, etc. Obviously it must be achievable, and that's why the Powers that be want me to complete the Work Request as detailed. I could email you the document so far if it would be of interest at all to you - won't be offended if you don't.

My previous job we used SAN and had the same configuration I feel sure you are going to use. We had 2 servers, clustered with MSCS with 2 x 9.1GB mirrored for OS and APP. THen the SAN was configured with 18.2GB disks in RAID5 with a Hot Spare. Worked a treat, and we were able to guarantee 99.97% reliability contractually and maintain it.

So, to recap a tad; I still need to simply confirm that when one breaks a mirror at OS level, it won't damage the data?

Thanks again for your response.

John

 

[fraxx]

Shut down the server. Remove one disk. Start the server. It will complain that one disk is missing from the mirror. Press F2 to continue in degraded mode. (I'm not sure of the exact wording, but AFAIK F1 is to disable the entire volume, which you _don't_ want to do).
Think you have to press F1 a few minutes later. ProLiants like to stop waiting for confirmation if anything was bad during the POST.

Boot from a floppy with ghost on it. Ghost the volume. I suppose you need network support on the floppy to be able to put the ghost image on a network share.

After you're done, reboot the server. Press F2, then F1 as before.
I like to wait until the OS is running, then plug in the disk you removed again. It will rebuild automatically at about 1GB/minute. You can check the progress in the ACU.
You're sure you don't lose any data, since all caches are flushed when you shut down the server. Hence, since you remove the disk when the server is powered off all data is written to the disks.
/charles

 

[johnnybb2000]

Thank you for this excellent input sir! This is what I will try.

I will get one of my lads to try to get it to the Ghost stage, since with the Mirror in place it won't even get to GUI mode with Ghost, simply returns the error.

I have only one question, if one doesn't actually break the mirror, won't Ghost see is as the same - a RAID'd volume - and complain of the RAID array - i.e. Error msg was coming up about the 1023 cylinder etc. Sorry I am not on site with the server, or the Post-IT I wrote the error message on!

I will hit you back when I have got a report back.

Thanks again,

John

 

[fraxx]

I've never had a problem with Ghost and SmartArray RAID controllers. SmartArrays hides the physical drives from the BIOS and DOS and only presents the resulting mirrored volume. Perhaps you're using an older version of Ghost which can't handle more than 1024 cylinders.
What model of ProLiant and SmartArray is this? What size are the drives?
/charles

 

[Beaghler]

Charles-excellent advice- I wish I'd thought of it. As a belt and suspenders CYA -why not remove one disk and try as suggested. If Ghost still complains, put new disk in, allow to rebuild, then break mirror. If all goes well great. If it goes south, then there's a copy around to go back to. That covers everyone, just in case.

 

[johnnybb2000]

What OS - NT4 SP6a
What type of drives - 2 x 4.3GB SCSI WU
Controller - Symbios Logic (Compaq Spec, can get more details if required, but not on site with server today).
It also has a second RAID controller controlling a Storage array of 6 9.1 UW2 (5 RAID5 + 1 hot Spare) - disconnected for "safety".

And it is the only version of Ghost our company is licensed for, I think it is 6.2

 

[fraxx]

I'm not quite sure if Compaq uses Symbios Logic chips on the SmartArrays. It must be an older server if it's 4.3 GB drives. Are you sure it's actually hw RAID?
Or are you checking the onboard SCSI controller, which could very well be Symbios Logic. The mirrored drives should be connected to a SmartArray hw RAID controller.
/charles

 

[johnnybb2000]

OK Charles, and thank you for your assistance too, I am going back to the site where the server is on Friday, and will push the info through then. Please bare with me, the server is 150 miles away from me, and it aint the best of journeys!

BTW, I had a colleague carry out the "Shut down, remove disk, ghost, then boot and replace", but this gave the same Ghost error. However, the suggestion of the backup on the second disk may well be a good solution in the absence of the Ghost solution.

Thank you both.

Speak Friday.

John Brewster

 

[johnnybb2000]

OK Charles, and thank you for your assistance too, I am going back to the site where the server is on Friday, and will push the info through then. Please bare with me, the server is 150 miles away from me, and it aint the best of journeys!

**I am about to go there now, for my curiousity - will post soon***

BTW, I had a colleague carry out the "Shut down, remove disk, ghost, then boot and replace", but this gave the same Ghost error. However, the suggestion of the backup on the second disk may well be a good solution in the absence of the Ghost solution.

Thank you both.

John Brewster

 

[johnnybb2000]

Hmmmmm... Strange things happening now, but I am not sure if they are related or a consequent of anything I have been doing with the Ghost or Mirror proceedure - well that's what I'll be telling MY boss!!! I executed the Compaq Array Configuration Utility and it says that it cannot detect any Drive arrays!

Well, I have been into SCSI Adapters in Control Panel and all it says is "Compaq Drive Array". I am unable due to reboot due to testing at mo, but the box is functioning perfectly normal. The Symbios Logic Cards that are in there are controlling the other things i.e. EMC disks, and CD - so suggest irrelevant.

Anything you want me to do?

John

 

[connollyg]

John, As you obviously dont have these disks behind a SmartArray controller, and from your previous comments, are you using "Host Based Mirroring", ie its being done by the operating system, rather than by hardware?

Gerald

 

[johnnybb2000]

Yes, I guess we must be. Sorry to give you inaccurate information, but this has confused me a little; basically one goes into a Manual Integration via booting with SmartStart, mirror the disks using that process. Once this is done, it is I then boot up with a network boot disk and install from an unattend file and install the OS.

Does that make anything more clearer??.. Hope so. And appreciate the input.

John

 

[johnnybb2000]

Hi,

I have now resourced a spare disk, and have installed it as the secondary disk of the Mirror. The mirror has built and I have r4moved the disk. I have then replaced the old disk, therefore I have an image on the spare out of the machine. Will I be able to boot up with this and reestablish it as the primary of a mirror when/if I have to roll back?

TIA,

John