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New Member

SG500X - High Latency

Ever since installing SG500X switches in my network, i have had issues with database disconnects. I have 2 SG500X stacked together. I have many LAG groups spanning the 2 switches for redundancy. I recently installed an iSCSI SAN for 2 physical vmware hosts, and the latency between the hosts and the SAN makes it near unusable.

When looking at the switches, everything seems fine. When looking at the vmware cli, you can see all the latency occurring throughout the day. It shows significant latency for both vmware boxes over the iSCSI connections. The vmware boxes have different nic's as well (Broadcom and Intel), so it is not a vmware issue. I have worked with vmware to eliminate that as being the issue, and now have a call with Equallogic. The issue is everywhere, but it is more apparent with the new SAN/vmware set up.

Help!

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New Member

Just a follow up after some

Just a follow up after some troubleshooting - it appears the network is taking some sort of "hit" periodically. I have to narrow down where it is coming from, but it happens once or twice a day, and spikes all VM processor, network, disk, and RAM usage significantly when it happens (not constantly). I cannot say it has to do with the switches at all, but there is something happening. I have replaced almost everything over the 2 years this issue has been present. 

EDIT: Looks like the "hit" is from a Symantec virus update done simultaneously to all clients. This is not the issue I am having with overall latency though.

 

Silver

Hello,You mention that you

Hello,

You mention that you have those two switches stacked, and that you also have several LAGs going between them?  Those LAGs are not being used, in fact spanning tree is probably taking those links down altogether.  When the switches are stacked they basically act as one switch, so your current LAG setup is like plugging the switch into itself, which can cause loops.  Spanning tree will prevent those loops, usually, but I could see it causing some latency issues anyway.

Try either just stacking with your stack cables, or don't stack at all and just use 1 LAG with however many links you would like between the switches.

Let me know how that goes,

Christopher Ebert - Advanced Network Support Engineer

Cisco Small Business Support Center

*please rate helpful posts*

New Member

Hi Christopher, Thank you for

Hi Christopher,

 

Thank you for your reply. I have the 2 switches stacked via the 10GB stacking ports. I have LAG groups going to the devices, such as vmware boxes, uplinked switches for clients, portchannels on servers, etc. Since it functions as 1 switch, I would typically use 1 port from each physical switch to create the LAG groups to the non-switch devices for redundancy. Is this the wrong way to do it?

 

Mike

Silver

Ah, okay, I understand.  I

Ah, okay, I understand.  I thought you meant several LAGs between the two switches themselves.

I have seen several people set it up that way, where the LAG members are spread across the two stack members, and while it allows you to do that I have also seen it cause some issues.

You are correct that it builds in a bit of redundancy for you, but only if you also have redundant links from each stack member heading upstream.

Just as a test could you try setting up your LAG to your hosts where both links are on the same stack member?

Christopher Ebert

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