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SHR non-hot-swap disk failure simulation


Polar

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Hi all,

 

I have 2 x 8TB configured as SHR with 1-disk fault tolerance. To make sure that the raid function is working I was looking for a way to test this. When working on a linux computer i could Force-fail by software. Newer versions of raidtools come with a raidsetfaulty command. By using raidsetfaulty you can just simulate a drive failure without unplugging things off.

 

Is this also possible when running XPEnology? Any other suggestions on how to simulate this on a non-hot-swap system (HP N54L bios not modified)

 

Another question that is bugging me is this: Right now i have only 2 disks, and am assuming that the current setup is ment to work in a situation where disk 1 would fail, the second disk just takes over. This would mean that there is already a synced copy of the data available on disk 2, or not?

 

And what would the case be when I add a third 8TB HDD to the mix. The final goal would be to have 2 x 8TB = 16 TB data storage available + 1 x 8TB for 1-disk fault tolerance. It would be my assumption that if disk 1 or 2 would fail, disk 3 would step in. But then again the question would be, if I have data spread over disk 1 and 2, how does SHR knows what data to mirror on disk 3? Is there actual data on disk 3?

 

Thanks for clearing this technical dilema :smile:

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Not sure in your commands question. I would just turn off the NAS. Unplug a disk and turn on.

 

About your 2 disk vs 3 disk question. If you have 2 disks is like Raid1, if you have 3 disks is kinda like raid5 (I think?)

 

Anyway you always (by default) have 1 disk tolerance. That doesn't mean if "disk 1 fails then the disk 2 will come in". Its more like if any drives fail (just one of course) your data will still be there.

 

With 3 drives is the same, disk 1,2 or 3 can fail and you will still be able to read your data.

 

Just google SHR or Raid and have a read.

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"Its more like if any drives fail (just one of course) your data will still be there" ...

 

Haha !!! And that is the technical wonder I'm trying to understand :smile:. If I have 16TB of data, and only 8TB for failover... how does this work? If I only have a one-on-one failover system (like I used to have in Linux : one disk has its own "second" disk for raid). All data is continiously synced. If one disk goes belly up, the second already has ALL data. But I can't figure out how SHR does this with 16TB agains 8TB failover.

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