Array power loss question

[Lockie]

Hi all,

I currently have FreeNAS setup on an HP DL380 G5, which has an 8 bay HDD cage.
I recently came across another 2 of these for a good price and have ripped the HDD cages out from those.

As the server doesn't provision for extra HDD cages in terms of power, I decided to set them up externally and just rewire a standard desktop PSU to provide those drives with power.
In the midst of this, however, it occoured to me that if I extend my current volume with these drives and the power supply dies, I'll lose everything as the drives in the server are separately powered.

I then had the idea of also powering the HDD cage inside the server with that desktop PSU as well.

So my question is this:
If all the drives power down at the same time due to the external PSU dying, will it still break the volume?

I'm aware that this is less than ideal, but I'm wanting to know the implications of all the drives going offline while the OS is still running.
As far as I'm aware, the array configuration is stored on the disks themselves, so I don't think it would be a major? Other than potential data loss for anything not written at the time of power loss, which I'm not too concerned about.

Thanks all.

 

[BigDave]

So my question is this:
If all the drives power down at the same time due to the external PSU dying, will it still break the volume?

I'm aware that this is less than ideal, but I'm wanting to know the implications of all the drives going offline while the OS is still running.
As far as I'm aware, the array configuration is stored on the disks themselves, so I don't think it would be a major? Other than potential data loss for anything not written at the time of power loss, which I'm not too concerned about.

IMHO you are going to play with matches in a very dry field of high grass. Will you get away with it, possibly.
I'm almost sure you are not the first person to do such a thing, but I recommend you back up all your data
before attempting this. Perhaps a simple two drive mirror with a few files on the volume and start pulling the
plug and see what happens...
If things don't work out, your original volume (if removed first) will not go "up in flames" along with this experiment.

 

[Robert Trevellyan]

Your basic question appears to be, "What happens to my pool if I lose multiple drives at once." This was answered on Friday in this thread.

 

[Lockie]

From that thread:
"The pool will be in a faulted state and inaccessible. Generally reconnecting the drives and rebooting will bring the pool back. Any data buffered in memory that hasn't been committed in a transaction group will of course be lost."

I think that answers my question. My situation would be that ALL drives go down together due to power loss.

Dave has made a good point that occoured to me later, to get some more drives and do some testing.
I'll give that a try and see how it goes.

Thanks guys

 

[Robert Trevellyan]

get some more drives and do some testing

Yes, that's a very good idea.

Thanks for quoting the relevant part of the other thread.

 

[Lockie]

Got some drives and have done some testing. Pretty pleased with the result.
https://www.youtube.com/watch?v=a5gMlSHmdlM