Hey everyone,

 

I recently rebuilt my unraid server and I'm seeing some strange cache write speed behavior.  If I write to a user share that has use cache set to Yes via SMB I can copy at about 280 MB/s which is slow.  If I enable disk shares and do the same copy direct to the cache drive share I get well over 1 GB/s which is what I'd expect.  The only thing I've tried so far is enabling Direct IO but that didn't help.

 

The cache drive is a hardware raid of SAS3 SSDs.  The PC I'm copying from has a PCIE 4.0 nvme disk in it.   Diagnostics attached.  Any help would be appreciated!

 

Thanks

 

 

tower-diagnostics-20200309-1707.zip

It's normal. Shfs (the magic behind Unraid shares) has an effective speed limit of 300MB/s to 500MB/s depending on various factors.

 

What I have been doing is to have custom smb config that targets /mnt/cache directly (instead of enabling disk shares) to get max performance.

On 3/9/2020 at 9:16 PM, testdasi said:

...

 

What I have been doing is to have custom smb config that targets /mnt/cache directly (instead of enabling disk shares) to get max performance.

Hey, any chance you can do this "custom smb config that targets /mnt/cache directly" thingy?

Thanks

27 minutes ago, SpeedyVV said:

Hey, any chance you can do this "custom smb config that targets /mnt/cache directly" thingy?

Thanks

 

Below is what works for me.  I usually just write 1 file through the user share and then once the folder structure is created I do the rest of my writes through the cache share. Its clunky, but it works for now until I can think of a more elegant solution.

 

[cacheShare]
  path=/mnt/cache
    valid users = whoever
    write list = whoever

Thanks for the quick reply, but I am not sure I get how this works. i'm a bit slow

 

So are you saying you create a new user share called "cacheShare"?
Where are you creating this smb config?
I have Disk Shares enabled. Should I turn that off?

If you stop your array, go into settings, then click on SMB there is a section called "Samba extra configuration:"  That's where you paste the config I shared.  After you start the array you should now see an extra share when you browse to your server.  You don't need to create it under the "Shares" area of unraid.  I would turn off disk shares unless you need it for something specific.  

thanks for your help!

Works! U Rock!

47 minutes ago, noacess said:

I would turn off disk shares unless you need it for something specific.

What you've done is the exact same thing as enabling disk shares and not exporting SMB shares except for the cache drive.

2 hours ago, noacess said:

until I can think of a more elegant solution.

For all disk shares set Export=No,

except for cache set Export=Yes

2 hours ago, bonienl said:

For all disk shares set Export=No,

except for cache set Export=Yes

 

I was referring to my hack of copying a single file via user shares to create directory structures and then copying the rest of the files via the cache share because of transfer speed being comparatively slow through user shares when writing to cache.