Volume operations causing slowness across SMB

Thanks for all the replies.

I guess more information on the setup would have been helpful as well:

- WD Red drives, 4TB each x4 (RAID5)

- Under 10 users accessing the drive at a given moment

- Not using any SSDs currently; we are actually thinking about swaping out to a Synology setup for SSD caching (their decision not mine but I'm supportive)

- File structure consisents of 10 folders or so. The main "Projects" folder that everyone works out of is 700GB and contains 22,000 folders in the root of it (this does not include sub folders). Could the file/directory structure be improved?, ie- folders used to break the alphabet up. A-D, E-H, I-J, etc.

I have the snapshots setup, from my understanding, pretty ideal and I dont think that is the problem but then again, maybe I dont understand how snapshots work. Originally we were taking snapshots once an hour because we wanted hourly protection. This turned into a preformance problem and I could see right away on the Preformance Graphs in the webUI. Since then, I have reverted the snapshots only x2 a day (12am/12pm). We've had problems with a file that was incorrectly editted that we needed to restore that file from earlier that day, so that is why we have this interval.

Users are not complaining about the slowness between 12pm-1pm (which is the snapshot/prune timeframe), they are complaining about it when a user opens a 2GB Illustrator file, edits the file and then writes it back to the NAS. Accessing the volume during this save procedure is difficult for the other user(s) on the network. I was hoping from the screenshot that I provided, we could get a better idea as to what should be expected/unexpected with the given setup (you don't have the right RAID, you don't have enough memory, the NAS is too small, etc.- what is the bottleneck?)

This is a Monday-Friday 7am-5pm shop. The NAS works great now that I have the snapshots where I need them. Its just the random times when the NAS is "slow" and "sluggish" not between the hours of 12pm-1pm which is a given due to the snapshot taken.

As it was said by jak0lantash "600 IOPS is significant on a RAID5 volume of 6 mechanical HDDs" - if this holds true, perhaps they have outgrown the mechanical hard drives? Maybe the SSD caching is the next step? That is what I was hoping to find out with my post. is 600 IOPS ideal for mechanical drives? Should I set that as my ceiling? How can I improve this.

Thanks in advance.