Celerra NS-210 MTU size of 9000

Hi all. We have an Celerra NS-210 which is serving CIFs data out to multiple Windows server and workstation clients - this is predominately for departmental file shares but also redirected folders and Citrix UPM data.

There is periodically (but not predictably) a 'slow-down' on the NAS where enumeration of specific directories is incredibly slow (i.e. browsing over SMB from a windows client or server). Outside this file copy from this location is incredibly slow - 160GB worth of file data (small files) took around 42 hours. I can see that the MTU size on the Gb NICs is set to 9000 - which differs from both the connecting clients and the network infrastructure (Cisco Switches).

The configuration of the NAS pre-dates me and no one seems to know why jumbo frames would've been configured on this device. Is this standard? Given the MTU for the rest of the environment (standard 1500) - would it be prudent to test setting the NAS MTU to 1500?

Thanks for any help!!!

Responses(2)

kajibade

33 Posts

0

May 25th, 2016 01:00

What you describe does sound like the intermittent performance degradations you might see when there are TCP retransmissions on the network. Before you change anything at all, the best way to check what is happening is to take a trace of the network between the clients and the Celerra.

R

Rainer_EMC

8.6K Posts

0

May 25th, 2016 07:00

At least on the same VLAN all devices need to have the same MTU

Clients on a different VLAN/subnet can have a different MTU but it can create problems with switches/clients that cant keep up

Look for retransmissions

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