md RAID reconstruction hints & tips?

[falko]

If you use SuSE 10.0, you should have a 2.6 kernel. You can check with

uname -a

[mphayesuk]

Yes kernal 2.6....

So far its not worked.... I have found the drivers for my onboard sata raid that will work for suse 9.... so I am assumeing that it should also work with 10... also with the new adaptec card I thought about trying the 32bit version seeing as though the drivers that came with the card are for suse 8 and 8.1 and are 32bit drivers, I know that it should not make a difference but you never know.

I have also got fedora core 4 64bit to try as well as Linux Red Hat 9.1 and just in the middle of burning Debian Sarge 3.1 the whole 15 discs, so I am sure by the end of it all I should be able to get one of them working by the end of the week.

If anyone has any more pointers on anything to do with raid let me know.... thanks for all you help so far.

[mphayesuk]

Just a quick question am I right in thinking that if I get raid 1 working when I come to install Suse or Debian ect.... I should only see one hard drive in the partitioning table right..... and if I unplug the first hard drive the second one would just take over so all I need to do to test is shutdown the machine unplug hard drive 1 and power back up and the os should load right?????

I know thats the way windows would do but I am not sure about Linux... with it using grub/lilo ect....

Thanks

[falko]

Originally Posted by mphayesuk

Just a quick question am I right in thinking that if I get raid 1 working when I come to install Suse or Debian ect.... I should only see one hard drive in the partitioning table right.....

Yes.

Originally Posted by mphayesuk

and if I unplug the first hard drive the second one would just take over so all I need to do to test is shutdown the machine unplug hard drive 1 and power back up and the os should load right?????

That's right, too.

[ryoken]

ive finally figured out what was going wrong. 1st, let me clear up any misconceptions. linux software raid (provided by md) works well - it allows you to rebuild a raid1 array when they the drives are mounted. Yes, it is perfectly safe to rebuild/sync an array when drives are mounted.

the problems i experienced with crc errors, segfaults, missing files, etc. was caused by data corruption!! falko, you were on the right track with your link about the crc errors. although the data corruption was NOT caused by old/aged hardware, it was actually a "bug" in the implementation of SATA on my motherboard.

basically, if your motherboard is based on the nForce 2 chipset and it has an onboard Silicon Image 3112 (3114 too?) SATA controller (and im sure there are many people out here using this combination!), then you will experience data corruption on your SATA drives. the fix? update your motherboard BIOS to latest version and apply this BIOS setting (located in Integrated Peripherals):

EXT-P2P's Discard Time = 1ms

And thats it. No more data corruption. No more errors after resyncing/rebuilding the raid arrays! so md was not the cause of the problem after all! and it took me more than a week to figure this out. i wish the motherboard manual was more informative about this BIOS setting (the motherboard was released after the problem was resolved months ago!).

mphayesuk, you may see multiple partitions (eg. md0, md1, etc.) depending on how you set it up. also unless the kernel (and/or dmraid if it is available) has support for your raid controller, you will still see your hard drives individually (regardless of how you set it up in the RAID BIOS).

thanks again for everyone's help! i hope my description above will help others with similar problems in the future!

[mphayesuk]

ryoken can you explain step by step what you did.... I am still having trouble with this. This is what I am assumening you did.

DID NOT - setup raid on the motherboard ie did not use ctrl+A to access the raid controller and configure raid1

YOU DID - use the partition options in linux install to mirror/copy the partitions one both drives.

After linux is installed you installed other software to make raid work.

Thanks

[ryoken]

Originally Posted by mphayesuk

ryoken can you explain step by step what you did.... I am still having trouble with this. This is what I am assumening you did.

DID NOT - setup raid on the motherboard ie did not use ctrl+A to access the raid controller and configure raid1

YOU DID - use the partition options in linux install to mirror/copy the partitions one both drives.

After linux is installed you installed other software to make raid work.

Thanks

Yes, I DID NOT setup raid on the motherboard.

Yes, I DID use the partition options in linux install to mirror/copy the partitions one both drives.

BUT after linux was installed, I DID NOT install other software to make raid work. software raid support (md) was already provided during debian installation, hence raid was working immediately after i finished installing. nothing to reconfigure/fiddle around with afterwards.

this howto pretty much sums up what i did to get md software raid working:

http://emidio.planamente.ch/pages/li...t_lvm_raid.php

Please note that i DID NOT set up LVM - i skipped those steps.

hope this helps...