10GE TOR port buffers (was Re: 10G switch recommendaton)

[bas <kilobit () gmail com>]

Hi,

Is there a reason switch vendors 1U TOR 10GE aggregation switches are
all cut-through and there are no models with deep buffers?
I've ben looking at all vendors I can think of and all have the same models.

TOR switches as cut-through with little buffers, and chassis based
boxes with deep buffers.

TOR:
Juniper EX4500          208KB/10GE (4MB shared per PFE)
Cisco 4900M                     728KB/10GE (17.5MB shared)
Cisco Nexus 3064                140KB/10GE      (9MB shared)
Cisco Nexus 5000                680KB/10GE
Force10 S2410           I can't find it anymore, but it wasn't much
Arista 7148SX                   123KB/10GE      (80KB per port plus 5MB dynamic)                
Arista 7050S                    173KB/10GE (9MB shared)
Brocade VDX 6730-32     170KB/10GE
Brocade TurboIron 24X   85KB/10GE
HP 6600-24XG            4500KB/10GE     
HP 5820-24XG-SFP+       87KB/10GE       
Extreme Summit X650     375KB/10GE

Chassis:
Juniper EX8200-8XS              512MB/10GE
Cisco WS-X6708-10GE             32MB/10GE (or 24MB)
Cisco N7K-M132XP-12             36MB/10GE
Arista DCS-7548S-LC             48MB/10GE
Brocade BR-MLX-10Gx8-X  128MB/10GE (not sure)

1GE aggregation.
Force10 S60             1250MB shared
HP 5830                 3000MB shared

I am at a loss why there are no 10GE TOR switches with deep buffers.
Apparently there is a need for deep buffers as the vendors make them
available in the chassis linecards.
There also are deep buffer 1GE aggregation switches.

Is there some (technical) reason for this?
I can imagine some vendors would say that you need to scale up to a
chassis if you need deep buffers, but at least one vendor should be
able to get quite some customers with a 10G deep buffer TOR switch.

I understand that flow-control should prevent loss with microbursts,
but in my customers get adverse effects, with strong negative
performance if they let flow-control do its thing.

Any pointers why this is, or if there is a solution for microburst
loss would be greatly appreciated.

Thanks,

Bas