SMB Speed goes down to <1MB

[Towley]

Hello there, I have this problem since some time.

Quite often the Copy Speed goes extremely down.

 

Unraid 6.9.2 ; Win10 ; 1GB LAN ; SMBv1 deactivated

 

When I want to copy something to the Server the usual speed is ~113MB/s. Sometimes I get this without problems and sometimes I get this problem.

First I get the normal Transferspeed and then after some minutes it suddenly goes down to ~1MB, without any Error Message or whatever.

There is nothing in the Log.

Sometimes there will be an Error (haven´t seen it since some time), but in most cases I have to abort the Transfer and begin anew. OR I can change something in the Share Settings, then the Transfer will be interrupted and I can directly resume it after an button press.

 

The Files I transfer are not small. The smallest are 5GB up to 80GB.

It makes no difference if I use it with or without Cache.

It makes no difference which HDD I use.

 

Ideas? It´s really frustrating....

[Frank1940]

What is the total size of the transfer?  The reason for the question is that it sounds like you might be filling up the cache drive.  IF that happens the remaining files will be written directly to the array.  If you spin down your array drives, the transfer would stop completely until the array drives have had time to spin up. 

[Towley]

My Cache is only 120GB, but as I have said, I do not use a Cache Drive with this Share.

[Frank1940]

Post up a diagnostics file after you have had the problem and give us the times and date when the transfer started (approximately) and when the problem started (as close as possible). 

[Towley]

Is there anything I have/can delete from this folder?

 

And i just copied a File from a folder to another in the same Share and the Speed was completely wonky. Mostly around 10MB´s, but sometimes went up to 50MB/s...

[Squid]

At any given time, the speed being given is meaningless.  The important thing is the time it takes vs the size of the file.  IE: The average speed.  If you're moving / transferring many small files, then every OS (including locally on Windows) has massive amounts of overhead in handling all the metadata changes, directory updating etc.

 

When you're transferring to the server from another system, the system is going to use memory as a "cache", hence why you're seeing the theoretical line speed of 112-113MB/s, and then once the memory gets filled, it has to start dumping the memory to the much slower hard drives, so you will see the transfer rate drop very significant, and then pick back up, drop again etc.  It's the average speed that's the important metric here.

 

One of Unraid's tradeoffs is that for the default settings (Settings, Disk Settings - md_write_method) is that it's read/modify/write.  This default means that only the hard drives involved in the write are active (whichever data and the parity(s) (others can stay spun down), but write speeds by definition are ~4x slower than the theoretical maximum of the hard drive.  By changing that setting to reconstruct write, you will tend to hit the maximums of the slowest hard drive present at the expense of every drive has to be involved (spinning up if necessary)

 

Copying files from the same drive to the same drive, is the worst of all worlds on any OS for speed, as it has to read the contents, wait for the drive(s) to spin back to the appropriate sectors and then write the contents, wait the drive(s) to spin back around for the next read ad nauseum.

 

Windows (ie: SMB3) is identical in speeds for transfers / moves within the same server as the entire system is smart enough to realize that if the source and destination are both on the same server then don't bother moving the data back and forth on the network.  EG: On my 2.5G network I can quite easily hit 7G/s via Windows copying files between a pair of WD Black NVMe's

[Frank1940]

38 minutes ago, Towley said:

And i just copied a File from a folder to another in the same Share and the Speed was completely wonky. Mostly around 10MB´s, but sometimes went up to 50MB/s...

 

For the benefit of anyone who will be attempting to help you, please explain exactly how you were attempting to do this copy.  (Using the network, within the server, Using the GUI, what file manager, ect.)