Slow writes?

[thepregnantgod]

Drashna, got a new one for you - and don't know if it's beta related

 

When I copy a 20gb mkv file from my nvme (Samsung Pro 950) to a Sandisk Extreme Pro added to the Pool as a SSD Cache (via plugin), it starts with a 1.5gb copy speed, then deteriorates to 20mb/second or less.

 

Just a week I go it would do this but then slow down to only 120mb/sec which I didn't notice/pay attention to.

 

Thinking that perhaps it was bypassing the SSD plugin and writing to a mechanical green drive, I opened up Task Manager/Performance tab and watched which drive was getting the write access - it was in fact the SSD.  So, the pool was directing the writes from the nvme to the SSD but I was still seeing very, very slow writes.

 

Suspecting the pool, I removed the SSD from the pool, added a letter and duplicated the exact same 20gb mkv copy from nvme to SSD.  It started at 1.5gb copy and then slowed down to 400mb/copy.

 

The variable is the Drivepool.  Additionally, it's something in the newest betas which I always use.  I will remove the beta and go back a month or so and retest to confirm.

 

It's my understanding that with the SSD cache setup, it should act like a straight copy from one drive to another and then duplicate after the copy is finished.  

 

Additionally, I've been converting my individual green drives to REFS but in this situation neither the nvme or the SSD are REFS (I suspected the error correction function on it might slow it down - so I made sure both are NTFS).

 

Oh...and memory leak (

[thepregnantgod]

Drashna, this morning I tested again.

 

I uninstalled the memory leak beta and went back to one in Mar.  Memleak problem solved.

 

However, I added the ssd to the pool and configured it via the plugin to get the files first.  

I then copied a 20gb .iso over to the pool.  The copy speed still bottomed out halfway through at about 10mb.  (Note, this doesn't happen when it's a separate ssd drive not attached to the pool).

 

I opened up Task Manager to see which drives were getting the data and the SSD was not getting the data.  

 

In fact, what I noticed was two of my green WD3tb drives were getting the data simultaneously.  

 

Does Drivepool duplicate on the fly?  It was my understanding that I could copy a file to the pool (ideally to the SSD) and then when it balances/duplicates it would move that file over and duplicate it.

 

If it does duplicate on the fly - what would happen if I connected two identical SSDs and configured both (assuming the plug in works this time) - would the file be duplicated simultaneously on the SSDs then copied over to the slower drives during balancing?

[Christopher (Drashna)]

If duplication is enabled for the destination folder, then yes, the data is written to all destination drives in parallel.

 

So if you're using the SSD optimizer and only have a single drive, then yes you will see slower speeds, as it will be slowed down by the non-ssd drive.  

 

So if you're using the SSD optimizer, you really do need to have 2+ SSDs installed and configured for this, or you won't see the benefit from the SSD Optimizer balancer.