After installing a RAID 1 system, you should not shutdown the system until 
the system has a chance to complete the sync of both disks.  Maybe this is 
the reason for your problem.

I'm a little confused why you want to deactivate the second channel and 
reactivate it once a week to resync.  I have systems that have run with both 
disks for 4 years or more without any problems.  I think this is the way it 
is supposed to work.  The way you are doing it you are better off not 
configuring the system as RAID and simply doing a manual sync once a week.



Timmy wrote:
> Hi Roelof and others:
> I uninstalled the SiI software raid card and installed SL 5.1 again!  SL 
> 5.1 seemed to be able to set up a RAID pair by itself even without the 
> add-on raid card!  Everything was very smooth.
> 
> My config is:
> 2 x 160GB SATA harddisks installed on 2 separate SATA channels.
> 
> My idea is to keep one hardisk as working system disk 24 hours (science 
> calculation, business, BT, everything etc and therefore it will be worn 
> out to death easily ;) and the other  harddisk as Spare disk.  It will 
> be rebuilt and cloned per week against the working system disk.  Another 
> file backup software will take care the incremental backup everyday! 
> Sound very perfect!  ;)
> 
> Ok! After the above mentioned SL 5.1 system was built and became stable, 
> I shut down the computer.  Then, I turned on the computer and 
> deactivated the 2nd SATA harddisk (named sdb) from within BIOS.  SL 5.1 
> booted with the single hardisk(sda) successfully (It claimed Degraded 
> RAID mirror when SL 5.1 started up).  I ran the system for a few days.  
> Then, I activated sdb again and hoped that SL 5.1 could rebuild it and 
> cloned sda to it.  However, SL 5.1 claimed that it could not find many 
> files and stopped at the command prompt.  I rebooted the computer, 
> deactivated sdb again in the BIOS and booted to SL 5.1 successfully with 
> only sda again!
> 
> So, I face a problem:  How to REBUILD / CLONE sda to sdb with Linux 
> command mdadm??  :((
> 
> 
> Timmy
> 
> P.S.  After I had unplugged the SiI software SATA RAID card, SL 5.1 
> never stops at RedHat Nash 5.19.6 ..... any more.  I guess this model of 
> card is not compatible with the current SL 5.1!  Avoid it!  :((
> 
> 
>> I never understood why redhat included the alpha quality dm-raid 
>> drivers. I call this alpha, since basic functionality like rebuilding 
>> a raidset (!) still is missing. DM-raid is a kludge to be able to do 
>> dual-boot with a windows system using these raid drivers.
>> Never, ever use dm-raid on a server. Use mdadm instead. It performs 
>> just as well (dm-raid is also softwaid after all) and it is stable.
>> If you only need mirroring, you can also use LVM to create a mirror. 
>> (I never used that myself, YMMV)
>>
>> Another advantage of mdadm is that it is hardware  independent. Your 
>> raidsets will keep on working even when transferred to a different 
>> brand of sata controller.
>>
>> By the way: if you try to install an mdadm based raid system on a 
>> drive that previously has been part of an intel/promise/highpoint raid 
>> set, it will probably fail after the first reboot.  This is because 
>> the dm-raid system is not active during the anaconda run, but is 
>> activated before mdadm in the regular startup. DM-raid will detect the 
>> old raid signature and lock the disk, preventing mdadm from using is. 
>> Apart from a complete disk wipe, you can set the 'nodmraid' kernel 
>> parameter in grub to prevent this from happening. Destroying the old 
>> raid-set using the bios tool before installing mdadm often will not 
>> work in my experience.
>>
>> Roelof
>>
>> Timmy wrote:
>>> I have installed SL 5.1 many times!  The file system can be corrupted 
>>> easily!  I don't know whether it is RedHat Linux's weakness.  Here 
>>> are my experiences:
>>> Case 1.
>>> The system might stop here at boot time:
>>> RedHat Nash 5.1.19.......
>>>
>>> After rebooting, it might boot normally or the system went corrupted 
>>> and no more boot again!
>>>
>>>
>>> Case 2.
>>> I installed 2 SATA harddisks as mirror pair on a SiI SATA software 
>>> RAID card.  Installation is successful but after several days' 
>>> operation, the system could not read the RAID pair.  Formatting was 
>>> needed.
>>>
>>>
>>> Case 3.
>>> After several days' downloading of a movie file through Ktorrent, the 
>>> file system went corrupted again!  Formatting harddisk required.
>>>
>>> I heard that downloading BT file hurts hard disk very much.  However, 
>>> Case 1 and Case 2 do not have any relationship with BT task.
>>>
>>> Any technique or trick to avoid this?