FreeNAS transfer speed drops after 30 minutes of uptime

[Pietroos]

Hi to all, yesterday I have installed on one of my servers FreeNAS, the average write speed is 50MB/s, but after 30 minutes of uptime, the write speed goes to 1.5MB/s, I have tried to modify some configs in the settings but nothing.

I have created a pool with my two HDDs in mirror, and one SSD fot cache

There is my server config:

• Fujitsu TX120 S3
• Intel Pentium G620
• 4GB DDR3 ECC Unbuffered (I'm waiting new ram to upgrade to 8GB)
• 2x SSHD Seagate FireCuda 1TB + SSD Kingstone 32GB

Do you have any advice?

 

[Pietroos]

After some tests I figured out is a Samba fault, if I restart the samba service the speed goes back to normal, but I haven't yet figured out why this happens

 

[MikeyG]

I'm not sure why Samba would be causing issues, but noticed that you said "one SSD for cache." Do you have an SSD assigned to L2ARC? If so I'd remove it. Since 8GB is the minimum for FreeNAS to run correctly, it may not be worth troubleshooting anything until you meet those requirements.

You many also want to specify what version of FreeNAS you are running and how you are getting those test numbers.

 

[Pietroos]

For first I tried to remove the cache SSD, but nothing. Anyway I think the problem is not the ram but is something with samba, if I try to stop and start only the samba service the problem is resolved, and if I continue transferring files the problem will not occur until I stop (and after some minutes of "standby").

My version of FreeNAS is the last: FreeNAS-11.3-U2.1

 

[Pietroos]

I've tried to add 8GB of RAM, and the problem is still here, after some minutes the SMB performance goes down

 

[Pietroos]

And now that I pay attention to it, the ftp server does the same, but it starts working again as soon as I restart samba

 

[Elliot Dierksen]

While 8GB may be the stated minimum, most people find the 16G is really required. This is particularly so on new versions like 11.3 that you are running. https://www.ixsystems.com/documentation/freenas/11.3-U2/intro.html#hardware-recommendations
I would be interested so see if you are swapping because you don't have enough RAM. You can run top from a shell prompt to get some idea.

Looking at your swap utilization from memory reports could also tell you something.

 

[HoneyBadger]

Are you writing for the whole time, and then seeing the speeds drop?

SSHD Seagate FireCuda 1TB

These are shingled drives. Early Seagate hybrids weren't but the new ones are.

 

[Pietroos]

@Elliot Dierksen The server is not swapping, just checked now (but the transfer speed is low), and the server has never used swap.

@HoneyBadger When the speed is normal, and I'm writing the speed is constant (Around 50MB/s in WiFi and 120MB/s via Ethernet), but if I don't do any transfer for a while next time the speed is 1.5MB/s (In WiFi and via Ethernet this even with thee different devices).

 

[Pietroos]

These are shingled drives. Early Seagate hybrids weren't but the new ones are.

If I remember correctly, the shingled drives are the +1TB ones

 

[HoneyBadger]

If I remember correctly, the shingled drives are the +1TB ones

Can you post the model number? The legacy "Laptop SSHD" wasn't, but the "FireCuda" branded ones were SMR across the table according to various end-user reports and looking at platter density. 2TB in 7mm though pretty much immediately says "SMR".

I'm not sure if the Seagate FireCudas report their reshingling as deletes, but you could check gstat -p to see if your drives are reporting high activity when you aren't putting any outside workload on them.

 

[Pietroos]

Can you post the model number?

The model number is: ST1000LX015. My drives are produced in Aug 2017 but they are never been used before

I'm not sure if the Seagate FireCudas report their reshingling as deletes, but you could check gstat -p to see if your drives are reporting high activity when you aren't putting any outside workload on them.

If i do the command in shell most of the time (When I'm not uploading files) shows all at 0 but sometimes show this: (The two SSHD drives are ada0 and ada1)

 

[Pietroos]

Anyway the problem is on all the drives, i tried to install a Seagate Barracuda (ST500LM034) and some SSDs however it behaves the same way

 

[Yorick]

SSDs are in their own pool? Sorry to ask extremely basic questions.

 

[Pietroos]

SSDs are in their own pool? Sorry to ask extremely basic questions.

Don't worry for the basic questions. The SSDs are in their own pool

 

[HoneyBadger]

Seagate Barracuda (ST500LM034)

Also SMR based on the pull from page 6 here:
https://www.seagate.com/files/www-c...op-fam/barracuda_25/en-us/docs/100818135e.pdf

Shingled magnetic recording with perpendicular magnetic recording heads/media.

The fact that your drives are showing huge %busy values when you aren't putting outside load on them would suggest they're busy reshingling themselves. If you let it "sit" for a few hours, do they eventually settle down and let you write a bunch more data to them before slowing down to a crawl again?

 

[Pietroos]

Also SMR based

Is it a bad thing for a nas that they are SMR based?

If you let it "sit" for a few hours, do they eventually settle down and let you write a bunch more data to them before slowing down to a crawl again?

I tried this yesterday but nothing, the speeds are blocked to 1.5MB/s, even now even now the speed is blocked

 

[Pietroos]

Another thing, now the speed is "blocked" and if I try to put something in the drives, is uploaded (Very slowly), but if I check in shell the %busy of the drives is all the time 0

 

[HoneyBadger]

Is it a bad thing for a nas that they are SMR based?

Yes, they lead to the kind of pathological performance issues seen here. SMR drives suffer badly when they're asked to rewrite data that's "underneath" a shingle - think about shingles on a roof. If you have to replace a failed shingle that's halfway down your roof, you need to "lift up" the ones around it. But imagine you could only do them in entire stripes from the peak of your roof down to the edge. That's "shingling" in a nutshell.

I'm curious though that you mentioned you have SSDs doing the same thing - what model are they?

 

[Pietroos]

what model are they?

The first i used is an old Kingston with 32GB of space, and the other one is a Samsung 860 QVO 1TB