QuTS - Data tiering - HDD - SSD

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danoldenkamp
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Joined: Fri Sep 17, 2021 4:27 am

QuTS - Data tiering - HDD - SSD

Post by danoldenkamp »

So QNAP decides to change to the new OS from QTS to QuTS with a ZFS file system.
Great.

How do we do data tiering on the new QuTS Hero?

I read there is a way to have a single folder share / repository across mutliple RAID groups, but can't figure it out.

I have SSD drives and HDD drives.
I want a volume to span across and shuffle the hot items to the fast disks.


When I try to add another RAID group to a storage pool it says its going to stripe them so a single failure results in all failure.
Maybe that is fine, but when I add the disk I get the error: RAID groups can contain the same type of storage medium.

Won't let me mix HDD / SSD.


QNAP touts that QuTS Hero is so much better than QTS for compression, de-dupe, performance, journaling of disk writes.
Can we mix HDD and SSD into a single pool?
Will it tier the data like a SAN?


TS-h1277XU-RP version h5.0.0.1772 (2021/08/26)
QNAPDanielFL
Easy as a breeze
Posts: 488
Joined: Fri Mar 31, 2017 7:09 am

Re: QuTS - Data tiering - HDD - SSD

Post by QNAPDanielFL »

QuTS Hero does not support Qtier.
And because it stripes data across all RAID groups in the storage pool, it is not good to mix SSD RAID groups with HDD RAID groups in a pool. If you do that, I would expect you mostly get HDD performance and waste the performance of the SSDs.

What Hero has going for it besides the extra data safety is better performance from HDD pools. Because ZFS natively writes to all RAID groups at once, you get more performance when you add more RAID groups. So there is good performance scaling with number of drives. Write Coalescing makes writes to HDD pools more sequential to improve write performance for many small writes. Prefetch makes reads more sequential when many people read at the same time. And in general, RAM is used as a cache in an effective way.

So, in general, Hero performs well. But there are at least a few use cases where normal QTS performs better.
If I know more about your use case I may have more to say about what setup may have optimal performance.
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