Speed Advice For NVME Cache Pool


mbc0

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Hi, 

 

I currently have a 1TB NVME Cache Drive and a 1TB NVME Unassigned drive in one of my servers,

 

I am thinking of creating a cache pool instead for redundancy and have been googling without much success to find out what would be the performance hit if I did that?

 

Any experience or pointers would be greatly appreciated!

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3 minutes ago, johnnie.black said:

Should be similar performance, though some users complain of bad performance with some devices in a pool, in that case latest beta should help due to the new partition alignment.

Thank you, I will start shifting some data and give it a go!

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20 hours ago, johnnie.black said:

Should be similar performance, though some users complain of bad performance with some devices in a pool, in that case latest beta should help due to the new partition alignment.

 

I have 2 NVME Drives both capable of 3000 mb/s write speed

 

Samsung 970 EVO Plus 1TB

Sabrent 1TB Rocket NVMe PCIe 1TB

 

I could write to both of those individually at 1000 mb/s using my fibre connection

 

Together as a BTRFS cache pool I am only getting 230 mb/s 

 

Will installing the beta make a 770 mb/s difference?

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2 minutes ago, mbc0 said:

 

I have 2 NVME Drives both capable of 3000 mb/s write speed

 

Samsung 970 EVO Plus 1TB

Sabrent 1TB Rocket NVMe PCIe 1TB

 

I could write to both of those individually at 1000 mb/s using my fibre connection

 

Together as a BTRFS cache pool I am only getting 230 mb/s 

 

Will installing the beta make a 770 mb/s difference?

Thats very weird, I have 2 intel 660p in a BTRFS cache pool in Raid 0 and i'm getting +-2.4 GB/s, what is the raid mode of the btrfs?, how are you testing the speeds?, you could try with the community apps "DiskSpeed", directly with dd command or even a VM to check you disk speed over the /mnt/cache.

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Hi,

 

They are BTRFS RAID1 for redundancy,

 

I have tested both drives at 3000 mb/s with diskspeed

 

The test is from my Desktop PC via my fibre connection (the reason I installed it) copying a 30GB file from my Desktop's NVME to the unraid cache

 

I have had 1000 mb/s when writing to both these drives individually for 9-10 months I was just looking for some redundancy on my cache drive. 

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39 minutes ago, mbc0 said:

Will installing the beta make a 770 mb/s difference?

It might male a considerable difference, especially since Samsung devices appear to be one of the most affected by the alignment issue, also to test use the disk share, not an user share, that also introduces some overhead.

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10 minutes ago, johnnie.black said:

It might male a considerable difference, especially since Samsung devices appear to be one of the most affected by the alignment issue, also to test use the disk share, not an user share, that also introduces some overhead.

OK, I will give it a go, I have been testing the same way I have been and need to use my system from Windows, the Samsung 970 has been my cache drive for over a year with superb performance, I bought the Sabrent 9-10 months ago and have been using it seperately (unassigned device) with also superb performance but now no longer need the sabrent so thought I would add some redundancy.  

 

So based on the fact that I have been using the Samsung as a single cache drive without issue, changing to the beta should help with the fact that the cache is now a pool rather than single drive? just checking it is not a fix for the samsung as it works perfectly.

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@johnnie.black

 

Just to update, I am now on the latest beta, removed both NVME Drives & Re-added formatting to MBR: 1MiB-aligned rebooted the server (just in case) but still only getting 230mb/s

 

I will post this on the other thread you linked as it is obviously where it has all been discussed.

 

Thanks

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