Really quick question about multipathing

[Jay_2]

I think I already know the answer to this one but I thought I would double check anyway.

I assume with Multipathing iSCSI I dont then need EtherChannel setup on our 2960G switches?

 

[AMD_Gamer]

I still don't understand what multipathing even is.

 

[altivec]

I still don't understand what multipathing even is.

Bonding or "Link Aggregation": 2 or more network connection using the same IP.

Multipath:
2 or more network connection, each using different IP.

Best practice of multipath would require 4 adapter and 2 switch minimum.
NIC1/2 (NIC1 Active on Switch1, NIC2 Standby on Switch2)
NIC3/4 (NIC3 Standby on Switch1, NIC4 Active on Switch2)

In best of best practice this will be even push to 2 storage with active/active replication so basically there no SPOF.

Most of the time it will be only 2 adapter (1 active/1 standby), 2 switch (1 active/1 standby) and 1 storage.

 

[patrickdk]

It really depends on how you plan to use the system.

If you bond/etherchannel/lapd, many clients can share the bandwidth, but no client can go beyond the speed of a single cable.

Using multipathing, your multipath setting has the option of either using it in a active/passive setting (so you get the same kind of result as above), or in an active/active setting, therefor exceeding the capacity of a single cable.

So what one you use, or using a combination of them, will depend on how many clients you have, and what acceptable min speed you want to a single client.

 

[Jay_2]

I also though that multipathing would load balance across the cables so even if only 10% of total bandwidth of 1 cable is used it would still put that across all the interfaces.

 

[patrickdk]

I also though that multipathing would load balance across the cables so even if only 10% of total bandwidth of 1 cable is used it would still put that across all the interfaces.

That depends on how you configure multipathing, and what kind of multipath settings both your devices support.

For opensolaris and esxi, I used roundrobin across all ports.

But some systems, it matters how you access them, like hp msa's, you only want to access a lun via it's active controller, doing otherwise kills performance and cache.