Slow transfer speed due to SSD cache acceleration

[Furyous]

On a rather small NAS like that, you could look into Qtier, where the NAS automatically moves the most used data to the fast SSD and the lesser used data to slow HDDs. I don't think Qtier has the same problems as the cache. In fact, accessing SSD pools over the network is freaking fast. It's just the caching that's borked.

Or just buy a NAS from a company that doesn't ignore such a MASSIVE flaw in their product for years? I don't think I will ever buy qnap again.

[drooplewx]

On a rather small NAS like that, you could look into Qtier, where the NAS automatically moves the most used data to the fast SSD and the lesser used data to slow HDDs. I don't think Qtier has the same problems as the cache. In fact, accessing SSD pools over the network is freaking fast. It's just the caching that's borked.

I'm new to Qtier, I think for using the Qtier I need to set up kind of RAID, 1 SSD + 1 HDD, right? I'm not sure if one disk failed, what can do to save the data.

[cryptochrome]

On a rather small NAS like that, you could look into Qtier, where the NAS automatically moves the most used data to the fast SSD and the lesser used data to slow HDDs. I don't think Qtier has the same problems as the cache. In fact, accessing SSD pools over the network is freaking fast. It's just the caching that's borked.

Or just buy a NAS from a company that doesn't ignore such a MASSIVE flaw in their product for years? I don't think I will ever buy qnap again.

Strongly agree. This was my last QNAP NAS for sure.

[Don]

Hi Guys,
I was thinking of purchasing a PCIe extension card and 2 1TB M.2 SSD for my TS-253d, I think I can save the money for something else now.

Those cards used to work but I don’t think QNAP supports them anymore as they want you to buy their QM2 cards.

[drooplewx]

Hi Guys,
I was thinking of purchasing a PCIe extension card and 2 1TB M.2 SSD for my TS-253d, I think I can save the money for something else now.

Those cards used to work but I don’t think QNAP supports them anymore as they want you to buy their QM2 cards.

Sorry, I was thinking QM2 cards, but typing PCIE cards

[galosu82]

It took three months of back and forth with the QNAP Support Team, but apparently, the SSD cache issue is now fixed (firmware 5.0.0.1891).

[cryptochrome]

It took three months of back and forth with the QNAP Support Team, but apparently, the SSD cache issue is now fixed (firmware 5.0.0.1891).

Can't really confirm. It has gotten better, but I am still getting much higher write speeds over a 10 GbE network connection when I bypass the cache (cache enabled but very small block size bypass).

With cache: about 300 to 350 MB/s
Without cache: 500 to 550 MB/s

Thanks for involving support! Much appreciated.

[galosu82]

My cache settings:




The speeds I'm getting:

[cryptochrome]

Right. Now go into your cache settings, select random I/O and set the block size to 256 KB and run the test again over Ethernet. I am getting faster speeds then (it bypasses the cache as AJA uses larger block sizes).

[galosu82]

After disabling the cache completely…

[cryptochrome]

Well, good for you that it works for you. On my NAS, it's still the same as before. Cache is slower than no cache.

[galosu82]

What is your firmware version? 5.0.0.1891?

What is your hardware configuration?

[cryptochrome]

Yes, Firmware 5.0.0.1891 on a TVS-1282T, Raid 6 disk array.

[galosu82]

Pretty strange. I've no idea why you are getting slow speeds both with and without SSD cache. Theoretically, your NAS is more powerful than mine (I have a TVS-672XT).

[cryptochrome]

Oh the bottleneck for sure are my disks. The Raid-6 array isn't the fastest, the WD disks are quite dated. So I will never saturate a 10 GbE network link when writing to that array (when reading, I get 10 gigabits maxed out). My hope has always been that the cache will increase the write speeds, but it has always decreased the speeds. And unfortunately, whatever they fixed in 5.0.0.1891 to make it work for you, it hasn't fixed it for me.