Need some input on network latency issues

[neotechnet]

Hi all, I feel like I'm chasing a ghost on this.

Network workstations are almost all Macs.

They have Meraki switches and wifi.

2 Dell servers running VMWare with Windows servers

A Synology 5 bay unit.

The windows file server maps the share drive to the Synology drive via a LUN share. So when a user on a mac opens a file on the share drive, it's mapped to the windows server share which in reality is just mapped to the Synology drive.

They get the spinning circle a lot on opening files.

There is no packet loss at all and memory usage on these devices are not near maxed out.

I'm out of ideas, can anyone think of anything? Other then the macs have a problem with going through a windows server to access files on the Synology?

 

[fencepost]

Packet monitoring to see where the pause happens?

 

[neotechnet]

Simple ping tests don't reveal any packet loss at all unless there is another tool you recommend.

 

[fencepost]

I meant something like Wireshark with a filter set so you're only capturing packets to/from one affected workstation, the server, and the NAS. You'll likely need to either configure the switch for packet capture (if it's a smart/managed switch) or run Wireshark on the server (which should be seeing all relevant traffic anyway). You'll also probably want to do it off-hours if the problem still happens then, just to reduce the volume of Server-to-NAS traffic.

This sounds like the Windows guest is using iSCSI to map to the Synology rather than VMWare having a datastore on the Synology, correct? I'm not sure how much detailed information I can give since I'm only peripherally involved with our ESXi and SAN setup, but I believe ours is set up with VMs stored on FreeNAS and accessed via NFS - I just don't have the depth of knowledge right now to dig too much into the merits of different approaches.

Basically what you'll be looking for is SMB traffic from the Mac to the server, then iSCSI? traffic from the server to the NAS and back. If you see a request from the Mac to the server then a 10 second pause before a request from the server to the NAS then look at things on the server. On the other hand if you see a request to the NAS and a 10 second pause before any significant traffic coming back from the NAS, that may indicate issues there. If the Synology is actually connected to by VMWare rather than by the Windows guest, you'll definitely need to do the monitoring from either the switch or possibly from configuring VMWare to mirror network traffic to another VM (never tried this).

 

[neotechnet]

Correct it's an iSCSI map to the synology.

Points well taken on wire shark.

 

[fencepost]

I'd also perhaps do a little looking around with a search such as "windows synology iscsi slow smb client" and see if anything relevant turns up.

Edit: Ah, this might be relevant: https://serverfault.com/questions/882000/limiting-smb-cifs-speed-in-windows-10 - basically is traffic to the workstations and traffic to the Synology on the same network connection? How large is the traffic? Is it possible that things are bottlenecking on the host network connection as it tries to both pull data from the NAS and talk to the workstation at the same time?

 

[YeOldeStonecat]

How many users total?
Any Windows users to compare same file browsing from?
How many switches....and how are they uplinked...what speed are the uplinks?
What drives in the Synology....what RAID type?
The 2x physical server hosts...horsepower of each? How many guest instances each? The specs of the file server that presents the iSCSI mapping?

 

[Markverhyden]

In addition what @YeOldeStonecat said. What is the timing on this behavior? New? Since the beginning? Any differentiation between wired and wireless? Versions of OS, including the servers? What files? What apps? File sizes? When does the pin wheeling happen? Only when being opened? What version of SMB is being used?

The last but biggest is why this arrangement? Seems like an unnecessary step to map a Synology through a ESXi VM.

 

[LordIntruder]

What about the energy saving settings on the NAS? If the drives are send to sleep after a period of time noone connects to the drive, the first connection takes as long as the drives need to spin up.

 

[PCskies]

If the share is being accessed by hostname, try using the shares IP address instead and see if 'spinning' still happens.

If the Windows file server manages DNS, make sure there is a route pointing the share hostname to the shares IP.