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Thomas Yarger
Beginner

Dell Equallogic SAN Design

All,

I have six Dell Equallogic SANs connected to two Cisco 3750X (Stacked) in a redundant fashion. I have enabled Jumbo Frames (9000) and I configured a Port-Channel connecting back to the Distribution Layer. Keep in mind, our SAN and Server traffic reside in the same VLAN. Our Virtualization Platform is Citrix / Xenserver. I'm currently seeing many Output Drops on the 3750X connecting the SANs. I believe the buffers are almost full. Any thoughts? Possible design recommendations?

Public buffer pools:

Small buffers, 104 bytes (total 50, permanent 50, peak 119 @ 1w2d):

     49 in free list (20 min, 150 max allowed)

     29870278 hits, 23 misses, 69 trims, 69 created

     0 failures (0 no memory)

Middle buffers, 600 bytes (total 25, permanent 25, peak 85 @ 1w2d):

     23 in free list (10 min, 150 max allowed)

     292659 hits, 39 misses, 117 trims, 117 created

     0 failures (0 no memory)

Big buffers, 1536 bytes (total 50, permanent 50, peak 260 @ 1w2d):

     50 in free list (5 min, 150 max allowed)

     7118336 hits, 87 misses, 261 trims, 261 created

     0 failures (0 no memory)

VeryBig buffers, 4520 bytes (total 16, permanent 10, peak 16 @ 1w2d):

     0 in free list (0 min, 100 max allowed)

     59 hits, 3 misses, 6 trims, 12 created

     0 failures (0 no memory)

Large buffers, 5024 bytes (total 0, permanent 0):

     0 in free list (0 min, 10 max allowed)

     0 hits, 0 misses, 0 trims, 0 created

     0 failures (0 no memory)

Huge buffers, 18024 bytes (total 4, permanent 0, peak 7 @ 1w2d):

     4 in free list (0 min, 4 max allowed)

     325240 hits, 13959 misses, 27855 trims, 27859 created

     0 failures (0 no memory)

Interface buffer pools:

RxQFB buffers, 2040 bytes (total 904, permanent 904):

     896 in free list (0 min, 904 max allowed)

     1676806 hits, 0 misses

RxQ0 buffers, 2040 bytes (total 1200, permanent 1200):

     700 in free list (0 min, 1200 max allowed)

     12989722 hits, 0 misses

RxQ1 buffers, 2040 bytes (total 128, permanent 128):

     5 in free list (0 min, 128 max allowed)

     18683526 hits, 766906 fallbacks

RxQ2 buffers, 2040 bytes (total 128, permanent 128):

     1 in free list (0 min, 128 max allowed)

     809774 hits, 6326 fallbacks, 0 trims, 0 created

     6326 failures (0 no memory)

RxQ3 buffers, 2040 bytes (total 128, permanent 128):

     1 in free list (0 min, 128 max allowed)

     6272522 hits, 51299 fallbacks

RxQ4 buffers, 2040 bytes (total 128, permanent 128):

     0 in free list (0 min, 128 max allowed)

     761106 hits, 906039 misses

RxQ5 buffers, 2040 bytes (total 128, permanent 128):

     64 in free list (0 min, 128 max allowed)

     64 hits, 0 misses

RxQ6 buffers, 2040 bytes (total 128, permanent 128):

     0 in free list (0 min, 128 max allowed)

     128 hits, 0 misses

RxQ7 buffers, 2040 bytes (total 192, permanent 192):

     61 in free list (0 min, 192 max allowed)

     513149 hits, 0 misses

RxQ8 buffers, 2040 bytes (total 64, permanent 64):

     0 in free list (0 min, 64 max allowed)

     3405180 hits, 3390852 misses

RxQ9 buffers, 2040 bytes (total 1, permanent 1):

     0 in free list (0 min, 1 max allowed)

     1 hits, 0 misses

RxQ10 buffers, 2040 bytes (total 64, permanent 64):

     1 in free list (0 min, 64 max allowed)

     5460093 hits, 822752 fallbacks

RxQ11 buffers, 2040 bytes (total 16, permanent 16):

     0 in free list (0 min, 16 max allowed)

     16 hits, 0 misses

RxQ12 buffers, 2040 bytes (total 96, permanent 96):

     0 in free list (0 min, 96 max allowed)

     96 hits, 0 misses

RxQ13 buffers, 2040 bytes (total 16, permanent 16):

     0 in free list (0 min, 16 max allowed)

     16 hits, 0 misses

RxQ15 buffers, 2040 bytes (total 4, permanent 4):

     0 in free list (0 min, 4 max allowed)

     16195688 hits, 16195685 misses

IPC buffers, 2048 bytes (total 300, permanent 300):

     290 in free list (150 min, 500 max allowed)

     822814 hits, 0 fallbacks, 0 trims, 0 created

     0 failures (0 no memory)

Jumbo buffers, 9240 bytes (total 200, permanent 200):

     200 in free list (0 min, 200 max allowed)

     0 hits, 0 misses

Header pools:

5 REPLIES 5
Bill CARTER
Contributor

Can you post the configuration? Enable flow-control. I also like the global command "buffer tune automatic"

http://www.cisco.com/en/US/docs/ios/netmgmt/command/reference/nm_02.html#wp1181763

How big of an impact will "buffer tune automatic"make? I will have to upgrade my 3750X so I can use that command. I do have flow-control enabled on the switchports. Is it necessary to enable flow-control on the uplink connections going to the Distribution Layer? Thanks

I think configuring flow-control on the uplinks would also help. Although I am not positive this is needed. I think the buffer tune automatic is worth it. Before upgrading you could try increasing "huge buffers max allowed". Start with 8.

I assume you're talking about adjusting the Huge Buffers pool? If not, I don't see the command "huge buffers max allowed" globally or under the interfaces. I'm on IOS 122-55.SE3. Thanks for your help!

The command is "buffers huge max-free #".

After readying this some more, it may be better to adjust the hold-queue on the interface. Can you post a show interface for a port experiencing output drops?