BTW, if you read the document @marce1000 provided, a (very) important note is:
From 3.6.3 or 3.7.2, the maximum value for Softmax can be modified with the CLI command qos queue-softmax-multiplier 1200 with 100 as the default value. If configured as 1200, the Softmax for non-priority queues and non-primary priority queue (!=level 1) are multiplied by 12 from their default values. This command would take effect only on the ports where a policy-map is attached. It is also not applicable for priority queue level 1.
I.e. just using qos queue-softmax-multiplier 1200 globally may not adjust the interface buffers.
The other thing to keep in mind, buffers are both reserved and a shared resource. I.e. to increase the amount of possible shared buffers, you need to, if possible, reduce reserved buffers, this is one of the aspects of "QoS tuning" I referred to earlier, but so is using the qos queue-softmax-multiplier 1200 command. Any QoS tuning chances making things worse, rather than better. That said, qos queue-softmax-multiplier 1200 is so often recommended, one can wonder why it's not the default (actually someone did post that as a questions on these forums). The answer is, rarely does it cause things to worsen, but that's not the same as never, and often it does help.
One of the big differences, between basic LAN switches, and higher end switches and/or Metro Ethernet switches, the latter often have more more hardware support, like more RAM for buffers (also why they tend to cost more).
