Re: Can zoning prevent bottleneck of SAN storage?

teru-lei · ‎01-17-2005

Hi All,

In SAN storage, many server connect to a SAN storage for data transaction, so that will create bottleneck in the storage because even if the storage connect more fiber to the SAN switch, like spanning-tree in switching network,just one link up, so there is 2Gbp bandwidth available to the storage. Can I use zoning to solve the problem? I means create one zone for server farm1 and one zone for server farm2. and one uplink to SAN switch of the storage belongs to zone 1 and one uplink belongs to zone 2. Can this method make both uplink up? Also does SAN have technique link etherchannel in ethernet network? Thank You!

Regards

Teru Lei

aolabisi · ‎01-18-2005

depending on your san switch platform - SAN-OS supports port-channeling. Your storage device has to support it too for this to work. that way you can have multiple interfaces connecting the same storage device.

you can also assign more BB credits to your storage device if it needs more.

Your zoning design will work, but you're simply moving the bottleneck away from the central switch to the distribution-layer switch... Zones are for access control and not bottleneck control. It won't make a difference if your 2 distribution-layer switches are in the same zone or different zones.

my $.02

dayo

teru-lei · ‎01-18-2005

Thank you! So is there a most efficient way to remove bottleneck in storage network?

tblancha · ‎01-21-2005

Zoning can be used to eliminate some traffic that is not needed. In a scenerio where everything is wide open WRT to zoning, then any event will be propogated to all devices-you might be able to think of it as a broadcast event. But if everything is zoned down to an initiator and the storage it needs to talk to, then any event that causes notifications will be contained within that zone and not fabric wide. This is not a significant amount of traffic, especially in a stable enviroment, but some devices are not able to handle a large amount of notification traffic.

Removing a bottleneck is a deeper issue than a simple answer. You could use BB credits, bandwidth, and locality to resolve congestion. I think the issue would be to analyze the source of the congestion-is it bad design? Is it massive data? Is it fabric data?

Rather than etherchannels, it is much preferable to use port-channels because FSPF will not re-converge in event of one link failing.

teru-lei · ‎01-24-2005

Hi tblancha ,

Thank You! It's seems that the design of storage network just like the design of switching network. We need to balance the traffic well to the fabrics and we need to increase the bandwidth where the bottleneck is located. Am I correct?

Best Regards

Teru Lei

tblancha · ‎01-25-2005

Yes, just like in a network situation, if there is a bottleneck, you have to examine why. Is it because there is truly not enough bandwidth? or is it some PC with a virus sending broadcasts? or the network filling up with retransmissions because a server cannot keep up to the clients? In the same way, SAN's have to be examined for their performance issues. IE, could we use a port-channel? Maybe more buffer-buffer credits or use an active/active loadbalancing scheme, etc.

j.sargent · ‎02-14-2005

The switch does support port-channels, but I don't know of any non-cisco device that supports it. In other words, you can't use a port-channel to connect your switch to your storage device. Until initiators and targets support them, port-channels can only be used between switches.

It would be awesome if storage and HBA vendors would start to support it!