How long to regenerate an array? Cerc Sata 1.5/6ch

Question

I have the Dell Cerc Sata 1.5/6ch with 4 x 320GB Drives configured with raid 5 on 2003 SBS

I have added 2 additional drives in the raid 5 array. The drives seem to have been added sucessfully and the Raid Storage Manager says that it is 'reconfiguring' 1,490.1 GB. The original 4 drives [894GB] were 80% full.

bios updated to 4.1-0 (7417)

driver version 4.1-1(7040)

My questions are: -

1) How long does this reconfiguring take?

2) Is the amount of time it takes based on how much data was on the original 4 drives?

3) Would it be faster to destroy the old raid and create a new one with all 6 drives and copy back the backed up data?

4) Disc Management container still shows 894.06 GB not the expected 1,490.1 GB. Is this correct?

There does not seem to be any way of telling how far the process has gone or even if it is happening at all!

Any help appreciated

Thanks

nigew

Dramba · Answer

Hello,   all your questions are very important and all answers depend on result of one or other operation, as you can notice some things happen or not when doing this type of operation. I will try to answer in same order :) :   Question 1 and 2 are really close : Reconstruction or rebuild will not take importance concerning data, when you got a Raid system and you want to recontruct or rebuild the system will see only virual disk, so for exemple if you have a Raid 5 3*320 Gb with only 100Gb of data, the controller will recontruct or rebuild 3*320Gb (so it will recontruct complete virtual disk). The time it takes for a reconstruct is very long (cannot unfortunally give you exact time for your configuration but I think 5-6 hours is a minimum in your case) because recontruct option will not only had new drive in Raid, it have to calculate the data for making aggregation on new drives and after doing a verify to check integrity of data.   Question 3 : As I explain in 1-2 points your right on this point, faster solution is to destroy and create a new Raid 5 with your 6 disks. you will have to backup data + initilialise new VD but you will not have to check constistency and to extend your logical drive, this point comes to Question 4 :)   Question 4 : As you noticed added drives are visible in Array (your array has increased) but not in operating system management tool, It's normal, because you have said to Cerc controller to add disk but not to operating system, so original partition cannot move by itself to new size. Normally you can notice a new unallocated partition in same physical drive in operating system disk management, if you want to add this to existing partition you have to use third party software to increase original partition (Dell developped a little soft named EXTpart to extend partition).   For conclusion after this long reading for you ;) , if you can, faster and better solution is to delete and create a new array with 6 disks, you will gain time, there is less data corruption risks and you start on new array well configured.   Hope this help !

nigew · Answer

Hi Dramba, Thank you for your reply. I asked about the length of time to regenerate because after 5 days there is no change. I was also expecting to see an unallocated partition appear and the end of the data when viewed in the OS Disk management. This has also not happened. I'm currently backing up [20hrs+ so far] and will revert to recreating the raid with 6 drives and restoring the data. Although a cheaper raid card than the Perc4, which I also run, it does not seem to be as robust. It does make me a little concerned if a drive were to fail. Would it actually regenerate a replaced drive as it is supposed to if the regeneration in this case has not taken place. Thanks nigew

Dramba · Answer

Hello Nigew,   Cerc 6Ch card detects fail disk as well as Perc 4, auto-rebuild option can be activated in bios (default enabled) and when a fail drive occurs your Cerc card will activate audible alarm. You just have to replace fail drive and auto rebuild start.   5 days is too much time for recontruct, You're right it has probably not worked.   Just a question about how you added disks to your existing Raid : Have you used Array manager and 'add member' option or have you do change is Cerc Bios ? If you have do it in Array manager, maybe if it doesn't affect your work you can just have a look in Cerc Bios array management to confirm that changes have been set in controller. This question because regarding to Cerc 6Ch documentation I haven't found recontruct option, maybe Array manager software allow to do it but not Cerc card (not sure).   For information here is link for Cerc 6Ch documentation : http://support.euro.dell.com/support/edocs/storage/RAID/CS6CH/en/ug/index.htm   Waiting for feedback !

nigew · Answer

Hi Dramba,
Having read about possible problems with earlier bios revisions I first updated the Bios to 4.1.0.7417 and 2003 WHQL driver 4.1.1.7040. This went without a hitch. I then tried to add the drives through the bios.

I have used Acronis to clone the raid drive to another SATA drive (11hs). Created a new RAID in the bios which is now 'Verifying 1%, 2% etc' when viewed through the Raid Storage Manager. At least I know its doing something now with the % sign! :-)

I will leave the verifying to complete as the RAID is almost unusable during the verifying phase. (copying data back is extremely slow during the verifying process).

Thanks for the link, I think the upgrade is now resolved.

Regards
Nigew

PowerEdge HDD/SCSI/RAID

How long to regenerate an array? Cerc Sata 1.5/6ch

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