Very slow cache

[zzzz]

Hi,

 

I setup my first Unraid server a few days ago and am experiencing 70-80MB/s write speeds my cache drive (hardware listed below). I'm currently using Unraid 6.8.3 (trial). I created a usershare across all 4 of my harddrives and set "Use Cache" to "Yes", and I do see the data being written to the cache drive just at speeds significantly lower than I would have expected. I installed "Fix Common Problems" but don't see anything related to the cache drive or the main array. I also used DiskSpeed to benchmark the NVMe incase the adapter was the problem, however the reported speed was ~1300MB/s, which is around what I would expect. I also did try enabling "Disk Share" then writing directly to the cache drive, but I also saw the same slow speeds. Both the Unraid server along with the Windows 10 PC i'm writing data from are wired directly to my router using Cat 6A and everything has gigabit ports, so I don't think there's any problems there.

 

Hardware:

CPU: FX-8370

RAM: DDR3 8gb

Motherboard: M5A99X EVO

Hard drives: 4x WD120EMFZ (12TB Easystore Shucked)

Cache: XPG SX8200 Pro 512GB (Attached using a PCIe x4 adapter card https://www.amazon.ca/gp/product/B01N09W21D/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1)

 

Any advice is much appreciated! 

 

[Vr2Io]

1 hour ago, zzzz said:

experiencing 70-80MB/s write speeds

It is normal in 1G network, no mater how fast of storage device.

[zzzz]

2 minutes ago, Vr2Io said:

It is normal in 1G network, no mater how fast of storage device.

Sorry if this is a dumb question, but why? Seems low for 1G, no?

[Squid]

1 minute ago, zzzz said:

Sorry if this is a dumb question, but why? Seems low for 1G, no?

Maximum theoretical is 110MB/s.  Once you take into consideration how parity works, then 70-80 is good.  You can speed it up by enabling Turbo Write (Reconstruct Write Mode) at the expense that every drive has to be spinning (ala a typical RAID environment)

[zzzz]

Just now, Squid said:

Maximum theoretical is 110MB/s.  Once you take into consideration how parity works, then 70-80 is good.  You can speed it up by enabling Turbo Write (Reconstruct Write Mode) at the expense that every drive has to be spinning (ala a typical RAID environment)

For the caching, I thought parity was only calculated when mover was kicked off?

[Squid]

You are correct there.  Post your diagnostics to see if there's anything else amiss

[zzzz]

I've attached the diagnostic info. Just removed the HDD serial numbers.

tower-diagnostics-20201214-1847.zip

[JorgeB]

Also good idea to run a single stream iperf test to rule out a network issue.

[dlandon]

You might want to take a look at this:

 

[zzzz]

10 hours ago, JorgeB said:

Also good idea to run a single stream iperf test to rule out a network issue.

Great suggestion, I ran an iperf test and it seems that I'm only seeing 680Mbit/s, so it seems to be a network issue. Will spend some time figuring out why my router isn't running close to gigabit.