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Mixing 5400 RPM and 5900 RPM in same vdev (RAIDZ2)?

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guermantes

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So I wanted to get 6 WD Red 4TB during Black Friday/Cyber Monday, but only managed to procure 4 drives (with different, but close, production dates) before the good prices were gone. Now I face the option of shelling out a bit more for the remaining two drives or getting two cheaper Seagate Ironwolf drives. I have opted for consumer, not enterprise drives.

It's a good idea to mix brands in order to not have all my eggs in the same basket, but one thing puts me off getting the Ironwolf drives:
The Ironwolf spins at 5900 RPM, whereas the WD Red spins at 5400 RPM.

Is it a bad idea to mix different-RPM drives in the same vdev?
 

SweetAndLow

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I would never mix bands it's a waste of time and effort for zero added value or benefit. You get miss matched vdevs and different speed. You need to burn in your drives not worry about manufacture dates and models.

Sure you can do it just fine.
 

guermantes

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Hi,
I fear your prose flies over my head. Bands? You enumerate disadvantages but then say I can do it just fine. I am afraid I don't know what to take away from the answer.

Burn-in i definitely do, following the guide here.
 

joeschmuck

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It is fine to mix and match different hard drive brands/models, you could even mix 7200 RPM with 5400 RPM drives in the same vdev if you like, it will work at the speed of the slowest drive.

What @SweetAndLow was saying is don't worry about drive batches, it likely will nto make a difference. For example lets say you bought 3 drives from NewEgg and 3 drives from Superbiiz and you created a RAIDZ2 vdev. Well if all three drives died from NewEgg then your pool would be gone. This is assuming that all the drives failed within a day or so of each other, a highly unlikely event. My advice is to buy drives that are on sale that meet the size, speed, and warranty you desire, and brand of course as most of us have a preference on what we like. I like WD Red line but I just bought HGST drives because they were on a good sale. I hope in 5 years that I love these HGST drives as much as I love my WD Reds.

The burn-in takes considerable time, for my 6TB drives it looks like 5 days, maybe 6 days when all is done. This is a SMART Short Test (2 mins), Conveyance Test (5 mins), Long/Extended Test (15 hours), badblocks (estimating 73 hours) and one last SMART Long Test (15 hours). While the burn-in testing is not a guarantee that your drives will not fail due to infant mortality, it's the best we can to to ensure the drive is working properly at the time.
 

danb35

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I would never mix bands it's a waste of time and effort for zero added value or benefit.
I wouldn't make a point of deliberately mixing brands, but I don't have any aversion to it either. But yes, ideally you'd have reasonably well-matched drives in a vdev.
 

guermantes

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Thanks for chiming in everyone! I went to the store intending to get Ironwolves, only to find a late-day offer on Reds, so I ended up getting Reds as I wanted originally. :smile:
Still I have learnt something, so for me this thread has not been moot.

Now my last four drives of the vdev are currently on their first long SMART test. The other two drives finished badblocks (default, four patterns) and the second long test this morning without errors. Looking forward to curiously do tmux attach repeatedly over the next three days in order to see how the testing proceeds. Can't wait to get this NAS adventure finally started and not just be building the system... (although it is half the fun)
 
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