asked on
RAID 1 on ML110 G4
Hi folks,
I have a question I need answering for educational purposes.
HP ML110 G4 server (little tower that I have crammed with RAM for virtual tests).
Now basically it comes with an onboard HP Embedded RAID controller made by Adaptec.
Here is the deal...
I created a mirror between two 74 gig raptors (lets call them A and B). Both work fine and Window server 2008 installation seems them as one. All good.
First test... I run windows, simply unplug a drive (A) to simulate a failure and windows keeps running perfectly.
I reboot and windows runs of the other drive as it should (B). Obviously in degraded state.
I shut the server down and do the following:
I plug the old drive in to simulate the return of drive (A) and unlplug drive (B).
Windows CANNOT start... Now what I want to know is WHY? and is this by nature even with the most expensive SmartArray 400p or Dell Perc 5i (and the other big boys)?
I 'BELIEVE' its because once drive A is removed it removes its register from the Array so when B goes and A returns it has no place in the array anymore?
Something to do with B becoming the new and final drive?
Once I rebuild the array in the BIOS (driver issues as to why I cant do it in windows), I can fail any of the two again while windows continues working.
I just cant plug the failed one back in and fail (unplug) the opposite one in the hope windows will boot up... It starts then blue screens.
Is this by RAID design or by the fact that this controller is just a cheap embedded sata controller?
many thanks..
I have a question I need answering for educational purposes.
HP ML110 G4 server (little tower that I have crammed with RAM for virtual tests).
Now basically it comes with an onboard HP Embedded RAID controller made by Adaptec.
Here is the deal...
I created a mirror between two 74 gig raptors (lets call them A and B). Both work fine and Window server 2008 installation seems them as one. All good.
First test... I run windows, simply unplug a drive (A) to simulate a failure and windows keeps running perfectly.
I reboot and windows runs of the other drive as it should (B). Obviously in degraded state.
I shut the server down and do the following:
I plug the old drive in to simulate the return of drive (A) and unlplug drive (B).
Windows CANNOT start... Now what I want to know is WHY? and is this by nature even with the most expensive SmartArray 400p or Dell Perc 5i (and the other big boys)?
I 'BELIEVE' its because once drive A is removed it removes its register from the Array so when B goes and A returns it has no place in the array anymore?
Something to do with B becoming the new and final drive?
Once I rebuild the array in the BIOS (driver issues as to why I cant do it in windows), I can fail any of the two again while windows continues working.
I just cant plug the failed one back in and fail (unplug) the opposite one in the hope windows will boot up... It starts then blue screens.
Is this by RAID design or by the fact that this controller is just a cheap embedded sata controller?
many thanks..
StorageServer Hardware
Last Comment
dqnet
ASKER
I totally agree with your answer - was hoping for a little more input from some other raid controller cards.
I too beleive that is by design but it would be nice to know the real deal...?
I too beleive that is by design but it would be nice to know the real deal...?
My cards are Promise and 3Ware and they both work that way.
Frankly I can't see it being set up to work any other way.
Once a drive has failed you don't want a RAID controller that -automatically- tries to use it again.
Frankly I can't see it being set up to work any other way.
Once a drive has failed you don't want a RAID controller that -automatically- tries to use it again.
ASKER
I totally agree..
But if it is a 'true' mirror surely a simple unplug of a cable should have all the data in such a state that windows can boot of it should you plug it back in?
After all, it is a replica of the other one? no?
Assuming you dont re-build and just stick it straight in removing the opposite drive?
But if it is a 'true' mirror surely a simple unplug of a cable should have all the data in such a state that windows can boot of it should you plug it back in?
After all, it is a replica of the other one? no?
Assuming you dont re-build and just stick it straight in removing the opposite drive?
>>>
But if it is a 'true' mirror surely a simple unplug of a cable should have all the data in such a state that windows can boot of it should you plug it back in?
<<<
It does.
But [with one drive there] don't 're-build' the array as in to restore data from a backup.
Re-build it as in to assign the drive to the array as if it were a new [and the only] drive.
Once that's done add the second drive and rebuild it to mirror the first drive.
-
The drives are only 'identical' until the point they aren't -both- running.
As soon as you run one without the other log files have changed and the page file changes [probably some other things] so they aren't actually identical anymore.
.
But if it is a 'true' mirror surely a simple unplug of a cable should have all the data in such a state that windows can boot of it should you plug it back in?
<<<
It does.
But [with one drive there] don't 're-build' the array as in to restore data from a backup.
Re-build it as in to assign the drive to the array as if it were a new [and the only] drive.
Once that's done add the second drive and rebuild it to mirror the first drive.
-
The drives are only 'identical' until the point they aren't -both- running.
As soon as you run one without the other log files have changed and the page file changes [probably some other things] so they aren't actually identical anymore.
.
ASKER
But whats the difference in just adding a new drive and re-building then?
I mean whats the purpose of:
>>>
It does.
But [with one drive there] don't 're-build' the array as in to restore data from a backup.
Re-build it as in to assign the drive to the array as if it were a new [and the only] drive.
Once that's done add the second drive and rebuild it to mirror the first drive.
<<<
I mean whats the purpose of:
>>>
It does.
But [with one drive there] don't 're-build' the array as in to restore data from a backup.
Re-build it as in to assign the drive to the array as if it were a new [and the only] drive.
Once that's done add the second drive and rebuild it to mirror the first drive.
<<<
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ASKER
Gotcha... Many thanks!
When you shutdown and switch drives and restart as far as RAID is concerned you have two failed drives.
They will be considered failed until you rebuild the array.
I 'BELIEVE' that's by RAID design, but I haven't used a wide variety of controllers.
On the other hand I've never used -any- embedded controllers. They've all been add-in cards.
.