QTS vs QuTS Hero for backup

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MGr871
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Posts: 2
Joined: Fri May 20, 2022 10:01 pm

QTS vs QuTS Hero for backup

Post by MGr871 »

Hi all, I think I may be stuck between a rock and a hard place due to the limitations of ZFS but wanted to ask anyway. We have ordered:
1 x TS-h1290FX-7302P-128G
2 x TL-R1220Sep-RP
1 x QXP-1620S-B3616W
1 x QM2-4P-484
24 x ST18000NM000J
4 x MTFDDAK1T9TDS
4 x WDS500G3X0E

The system is going to be used primarily for backups so configuration would be:
The 24 x HDDs in a RAID 60 with the 4 x U.2 SSDs in a RAID 10 for write caching and the 4 x M.2’s in a RAID 10 for the NAS’s OS, the NAS will be connected to the network via dual 25GB links. We use Veeam for our backup and its important to us to have immutability (I realise Veeam immutable backup is not available yet but have been assured its on its way!). Anyway I am stuck with the following Pro’s \ Con’s list at the moment when deciding between QTS and QuTS Hero:
QTS Pro’s \ QuTS Hero Con’s
QTS seems like it would be a lot faster for data transfer as QuTS Hero \ ZFS can’t support a write cache only read (pointless for a backup device).

QuTS Pro’s \ QTS Con’s
QuTS Hero can natively support immutability by placing time locks on folders giving me another way to implement this feature and use it to protect copies of files not covered by Veeam
QuTS being newer seems like the OS of choice moving forward

At the moment I am leaning towards the better features of QuTS Hero but hoping that the transfer speed isn’t too bad due to the limitations of ZFS (maybe a write cache is something that could be introduced later, I know that’s on ZFS not QNAP). Is their anything I have overlooked or anyone with experience of how big a performance gap we are looking at between QuTS Hero and QTS?
QNAPDanielFL
Easy as a breeze
Posts: 488
Joined: Fri Mar 31, 2017 7:09 am

Re: QTS vs QuTS Hero for backup

Post by QNAPDanielFL »

Are you using a tower U.2 unit with just 4 X U.2 for Cache and all the storage on 2 X Rackmount expansion units?
It seems like a not common setup, but there should be some ways to get good performance out of this.

QuTS Hero ZFS advantages are
1: Write Coalescing. Smaller writes are combined in the RAM to larger chunks to be written to the drives more sequentially. If you have Synchronous writes, you may want those system pool SSDs to have power loss protection for better performance since ZIL Synchronous IO goes to the system pool by default. Or you can have some compatible Optane SSDs as a dedicated ZIL space.

2: You can set the block size for ideal performance for a given file size you work with.
3: ZFS writes to and reads from all the RAID groups in the pool at the same time. So if you have 2 of the TL-R1220Sep-RP in 1 pool, you can get more performance in QuTS Hero because you write to both expansions at the same time.

QTS has the advantage of SSD cache with faster sequential performance and it can have a standard write cache. If you use write cache, I suggest a UPS because write cache can be dangerous if there is a power outage. QTS can also use qtier to take advantage of more of your U.2 drives.


Side note:
With this setup, you won't use most of your U.2 bays. Does Veeam let you use an SSD LUN to accelerate backups? If so, then you may have a better way to use the U.2 bays than as SSD cache.
MGr871
New here
Posts: 2
Joined: Fri May 20, 2022 10:01 pm

Re: QTS vs QuTS Hero for backup

Post by MGr871 »

Hi, Thanks for the response. I appreciate it is not a common setup but their are reasons for it including the possibility of adding 8 x U.2 SSDs in the future when cost goes down. While it does seems little odd to put a tower unit in a rack the alternative (TS-h2490FU) has more bays than we would use, massively reduced PCIe expansion and increased cost, all equipment is UPS protected so we feel its worth the trade off. Unfortunately I can't find anything in Veeam that would let me use the SSDs as a write cache or any other form of acceleration and while I appreciate that 24 disks in a RAID 60 will help speeds in ZFS it will be significantly slower than a write cache. The SSDs are only 2TB each so in a RAID 10 that will give me 4TB (enough for a cache but no where near enough to handle a backup). Even if I increased the size of the SSD pool so it could fit a whole backup then the problem of moving that data onto the main storage pool would be a bigger problem. Maybe the option of holding out for ZFS to add write caching as a feature is the best move as I don't to loose out on the immutable options I have with QuTS Hero even though QTS seems like a superior OS for this job.
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