disParity

disParity » General Discussion

1. paxtrix
   Member

   What would be my options (RAID 6) to protect against 2 drive failures or loss of parity drive? I'm current adding the last 3 drives to my parity (for some reason it would error whenever I tried to add all 13 data risk units. I thought this procedure, from what I found on the forum here, would expose my possible faulty drive but the process continues... It has taken several days to arrive at this point in the process on my WHS. My thought is to use the 2TB drive that I'm currently using as my temp drive (again great info on the forums as my c:\ temp location wasn't able to process my Blu-rays) to copy all parity data over to this drive and process 2 updates by changing the parity drive assignment in my config file. I would assume this would cover me in the event of a crash of the main 2TB parity drive. Would this allow for the recovery of 2 data risk units if I were to lose 2 drives?

   Thanks for the help & this is a great simple option to my previous FlexRAID! Nice Roland!!!

   Posted 4 years ago #

2. Roland
   Roland

   Hi paxtrix,

   sorry for the delay in responding, been busy with holiday stuff.

   Your question is complex and I'm having trouble understanding all the details exactly from what you wrote. To your main point though, there really is no way to protect yourself against two simultaneous drive failures using disParity. For my own data protection needs I regarded that case as so statistically unlikely as compared to a single drive failure that I did not even attempt to design for it. It would require a fundamentally different approach to the one disParity uses now.

   I'm not sure what having a second parity drive and running update twice, once to each drive by changing the config file, really gets you. That would be the same as running update once and then just copying your parity data to another drive. Yes, this would protect you against the case of the parity drive failing along with a single data drive (because essentially you've made a 1-for-1 backup copy of your parity) but it still won't protect you against the general case of 2 data drives failing.

   I hope that helps to clear things up!

   -Roland

   Posted 4 years ago #

3. paxtrix
   Member

   Thanks for the reply Roland; I trust your Holiday's were pleasant. The main reason for wanting multiple drive protection is b/c of the number of drives that my server has (I’ve lost 2 drives 1 after another b/4). I've removed 2 of the 15 2tb drives from the WHS pool to use as parity drives. I've started running two parity updates (changing the temp location and parity location) to give me a true 1 to 1 of the parity drive in the event that a parity drive crashes. It took 10 long days to acquire the parity drive for the 13 2tb drive that I have all 75% full. I don't want to repeat that process if I lose the parity drive, so I run the process twice, once for each of the 2 parity drives after new data has been added. BTW it took over 4 hours to make the initial copy of the parity drive, so rather than spend 4 hours each time copying the parity drive I just change the config file to point disparity to my back parity drive. It seems to be working great; it makes the same updates to each drive. After adding 1 blu-ray, the update process takes about 15min to create the updated parity. I would hate to wait 4 hours to copy all of the updated parity data over to the backup drive so running the update twice works for me. BTW I have the Norco 4020 case and will be adding a few additional drives in the coming days now that I have my software raid solution working again… Thanks to you sir!!! Thanks again!!!

   Posted 4 years ago #

4. Roland
   Roland

   OK, I see, yes doing it that way (running update twice) would be a lot faster than just copying the entire parity drive after each update.

   Just to clarify...when you say it took 10 days to build the initial parity, is that because you did it by adding one drive at a time and re-running update each time? A normal parity build should not take even remotely that long, even for 26 TB.

   Posted 4 years ago #

5. paxtrix
   Member

   When I tried to run the initial create it would error, when I check the forum it was similar to the issue another user had asked you about. I then would add 2 to 3 drives at a time in the config file and when I ran the update it would process 1 drive at a time anywhere from 12 to 24 hrs depending on the number of files on the drive. Drives with thousands of small files would take the longest time to process. I know the initial create would process all drives at once b/c all of the drive lights would be lit when it would start. It always failed after 1 to 4 hrs of run time so I ran the create and processed updates for adding the additional drives to see what drive was causing the issue. All drives processed completely without any further errors, just wondering if the controllers are having some sort of issue when all drives are spinning. Using Supermicro (2) 8-Port SAS/SATA Cards

   Posted 4 years ago #

6. paxtrix
   Member

   Well Roland you were correct! I balanced my WHS drives with a little utility and processed a new parity drive without a hitch. Instead of taking approximately 10 days to complete as it did my 1st time by running the update command to add each drive individually, it took just a minute shy of 24 hrs. Needless to say I was ecstatic that all 14 2tb drives process simultaneously as requested without crashing. I will continue to process two parity drives for redundancy or until I need the extra 2tb for the media server. I’ll state it once again, you’ve created a straightforward program that’s just simple to use and understand! For that my friend, I am grateful… Thanks again!!

   Posted 4 years ago #

7. Roland
   Roland

   Glad to hear it worked out!

   Posted 4 years ago #

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