Major Network Slowdown

[cscc]

We seem to be having a bit of a strange issue with our network at the moment. It is something which has gradually built up and is now getting worse.

 

In the mornings when the bulk amount of users log in, the whole network grinds to a halt. The odd thing is any machines on the network that have been logged in since the start of the day experience massive slow down, to the point where you cant do anything (the network switches seem to go nuts and pulse together simultaneously). The slow down can range from 3-5mins. The really frustrating thing is you cannot do anything locally as the machine just sits there with an egg timer until the network storm is over.

 

We use roaming profiles for both staff and students. Since the problem has started to become more prominent we have checked our fileserver for profile issues and found out student profiles are no bigger than 30MB. Some staff profiles are 60MB max (staff normally login before the students though).

 

Anyone have any ideas?

[K.C.Leblanc]

SOunds like either a network loop or a faulty network card producing lots of chatter.

 

Try installing Wireshark on a computer and seeing what MAC address all the trafic comes from.

[Dos_Box]

Let me guess, you have roaming profiles. Have you tried folder redirection?

[Nikthomas]

Let me guess, you have roaming profiles. Have you tried folder redirection?

 

Yeah that's what he says in his post haha!

[cscc]

Yep, we use roaming profiles. We have folder redirection setup for My Documents and Desktop. So profiles are normally pretty slim. Have tried wireshark on a couple of machines and there is no unusual traffic, even during the massive slow down periods.

 

The slow login for students isn’t really the issue, it’s fact that other machines already logged in experience huge lag for several minutes.

[penfold]

Does this problem only happen when the whole class logs on at the same time? If the problem has gradually happened, is it because your roaming profiles have grown over time? Try D_Bs suggestion of redirecting folders.

 

Edit: Took too long to type

[cscc]

Yep the problem only seems to happen at the beginning of each lesson when all the students log in at the same time. We have 6 ICT suites with 30 PC’s in each. All these machines are pretty much in use every lesson, all day long.

 

The user accounts have been split across 3 servers and the average profile size is about 12MB. We used to get this problem once every few weeks, but now it appears to be at the start of every period. The profiles of kids hasn’t grown enough to effect the network this much.

[Dos_Box]

It may be possible that your GPO with folder redirection on has become corrupted. Check the machines to see if local profiles contain my documents etc.

[cscc]

Just checked a few random machines in different rooms and within the profile directory My Documents is not there so the group policy is being applied correctly.

[timzim]

If the switches are pulsing it sounds horribly like a network loop (as K.C.Leblanc says above). If you can't identify a rogue nic it may be some little rotter plugging a cable from one network socket to another. Turn on Spanning Tree on your switches to see if that stops it. Then disembowel the offender (normally prevents reoccurrence).

[Earthling]

When we had an identical problem to yours, we finally came to the conclusion that our server/file storage set-up was the problem. Two Snapservers iSCSI'd to a four-year old Sunfire V20z finally became 'not up to the task'.

 

We outed the Snaps, bought a new Dell Poweredge with 16G memory and a terabyte of hard-drive (massive overkill on disk space, but hey-ho, it's cheap) and problem solved overnight, once we had migrated all the student, staff and IT support home folders and other stuff.

 

Well.............I say 'overnight', but it took a while to migrate everything, probably a week.

 

As for a loop, all the loops that our little darlings have created have been obvious in their immediate effect and haven't sorted themselves out after a little while....we've had to go and find them.