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How Are RAID Arrays Identified By Hardware?
Coward Anonymously Before Me asks: "This is more of a tech/hack question, but recently my highpoint controller forgot my disks were in a raid array. All the Disks still function, and have ZERO problems, aside from being not identified as still in RAID-0. All the data should still be there, but remains unaccessible to me, thus the question how and where would this kind of information be stored? On chip? MBR? and can the data be recovered without 3rd party interaction via free/open source toolkits? or even purchased software?"
Typically, there's a utility in the RAID configuration that stamps the drive as part of a set, marks the state (good, bad, rebuilding or hot-spare are most common) and some kind of versionig information.
I've ripped a few disks out of the array, mounted them as standard, reformatted and replaced the MBR, threw them back in the array, and still had them recognized as part of the RAID volume. The RAID card didn't like this much, however. :)
I think your best bet is to talk to one of the people who actually wrote the drivers for the card (you've got the Linux source, right :) or possibly see if you can get ahold of an engineer at the manufacturer and discuss ways of getting the information back.
Good luck!
There's so little difference between politics and jihad lately...
...I went to Google and found this:
"Where does the controller store its configuration? Disk, Ram, Rom ? Can it be saved or exported as a backup?
The config is in NVRAM on the controller, but there's also about a 4MB
"partition" (not really a partition, but config area) on each drive in the
array that stores information on things like position in the array, etc.
Alternately, try this link for the whole thread on the subject.
It literally took me 30 seconds to find it. Next time, try Google before posting, mmkay?
Cruising the internet on my TI-99/4A @ a whopping 300 baud!
Logical volume managers (AIX and Veritas anyway) store a unique ID on the disk, and then keeps track of what volumes are there, how they are configured, etc.
Hardware controllers generally reserve a small slice of disk to store configuration data. Sometimes this slice is marked unusable and can only be accessed by low-level hardware.
One of the big, unadvertised problems with RAID, particularly with new/buggy controllers, is that a controller failure can trash your data.
Unless you have the time & knowledge to reconstruct the data structures, a controller failure that screws up the configuration data on disk effectively destroys your data.
Conformity is the jailer of freedom and enemy of growth. -JFK
If your controller just spontaneously lost it's configuration, it's a problem with the card. Call the manufacturer and get a replacement. If they will configure it for you before they send it (which shouldn't be difficult for them), you should be able to just swap it in and go.
You'll need to do something like this, since you won't be able to get at the data on the drives unless you can hook them up to a RAID controller that will recognize the particular flare code etc of your setup.
If you can stomach losing the data (you backed up the important stuff, right?) then you could try starting over from scratch, but I would not trust your RAID controller if I were you. Replace it or don't use it.
Under capitalism man exploits man. Under communism it's the other way around.
I've worked quite a bit with AMI controllers and Adaptec. At work we looked at using an Adaptec ZCR card but chose not to for the following reason.
AMI Megaraid(and now LSI) write a bit of config info to each disk and to the controller. On these cards, you need to know the drive designations (which is drive1, which is drive 2, etc and the stripe size (how much data to write to the first disk before moving on to the second). On these controllers, if your card goes belly up you can usually put in a new card which will detect that your drives still have a configuration and use it. Otherwise, you can create a new configuration of the drives (same raid level, same stripe size, each drive with same designation) and it will access the data just fine on a reboot. (probably 75-85% of the time. The rest of the time you are just SOL and need to get out tape.)
Adaptec's ZCR card we were testing and going to ship had the unfortunate effect that when an array was created, it immediately initialized (format) all the data.
This is something you should check into. Perhaps the highpoint card will let you make a new array and reboot. Or it might automatically initialize and wipe out all your data before letting you use it.
Hope this helps
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