Replacing old disks in RAID5 on Alt-F

[Al K]

Hi João,

Great to see Alt-F development moving forward!

I have been using RAD5 on the DNS-323 for quite a while now without any issues.  I am getting concerned that my drives are very old (6 years now and counting) and thought I may want to head off problems by replacing them.

Do you have a recommended procedure for replacing the drives in a RAID5 array on Alt-F?

Or is it as simple as "pull a drive, replace drive (same size), and let Alt-F rebuild automatically"?

I have two RAID5 arrays, one is fitted with 2TB drives and the other is fitted with 1TB drives...I am also still on RC4 for both of them.

Thanks
Al

[João Cardoso]

On Monday, 9 October 2017 06:12:00 UTC+1, Al K wrote:

Hi João,

Great to see Alt-F development moving forward!

I have been using RAD5 on the DNS-323 for quite a while now without any issues.  I am getting concerned that my drives are very old (6 years now and counting) and thought I may want to head off problems by replacing them.

Do you have a recommended procedure for replacing the drives in a RAID5 array on Alt-F?

Or is it as simple as "pull a drive, replace drive (same size), and let Alt-F rebuild automatically"?

No, it is not that simple.

I think that has already being covered, and the procedure is similar to fixing a degraded RAID1 array, see 

https://sourceforge.net/p/alt-f/wiki/How%20to%20fix%20a%20degraded%20RAID1%20array/ and make the necessary minor adaptations

But now you have to do that for two (or three) disks, one at a time -- that is going to take a lot of time on a DNS-323, as at each disk replace step a full RAID5 rebuild will be done... and the failure of a disk (a single bit, in fact) at this step means data loss.

On the event of a real initial disk failure, not your case, and as usually disks for a RAID5 are bought together from same manufacturer and fabrication lot, then the probability of a second disk failure increases. That's why RAID6 appeared.

I have two RAID5 arrays, one is fitted with 2TB drives and the other is fitted with 1TB drives...I am also still on RC4 for both of them.

From the logs there have been only a couple of minor modifications on the RAID webUI since 4.0, and they regard creating new RAID devices.

Start with the 1TB Array. If you intent to do a backup first, then the possibly faster route would be to create a new fresh RAID after the backup being done and filling the new RAID from the backup. The backup and restore through the network (use *plain* ftp if at home, its faster) will also take ages, but that are two steps, against three rebuilds.

 

Thanks
Al

[Al K]

Hi João

No action needed here.  I am just putting this out there as an update to using RAID 5 on Alt-F.

Over the weekend, an internal 3TB drive in my DNS-323 failed.  It was part of a RAID 5 array using an external 3TB WD portable drive.

Following the instructions, linked below, worked perfectly, I was able to rebuild the array in the DNS-323 successfully.  

The total time for the rebuild took approx 3900 minutes.   

Thanks for ALT-F!

Regards,

Al