IBM pSeries manual Dropped switch packets

MPCI: sends = 14

MPCI: sendsComplete = 14

MPCI: sendWaitsComplete = 17

MPCI: recvs = 17

MPCI: recvWaitsComplete = 13

MPCI: earlyArrivals = 5

MPCI: earlyArrivalsMatched = 5

MPCI: lateArrivals = 8

MPCI: shoves = 10

MPCI: pulls = 13

MPCI: threadedLockYields = 0

MPCI: unorderedMsgs = 0

LAPI: Tot_dup_pkt_cnt=0

LAPI: Tot_retrans_pkt_cnt=0

LAPI: Tot_gho_pkt_cnt=0

LAPI: Tot_pkt_sent_cnt=14

LAPI: Tot_pkt_recv_cnt=15

LAPI: Tot_data_sent=4194

LAPI: Tot_data_recv=3511

5.12 Dropped switch packets

Lower than expected performance can be caused by dropped packets on the HPS switch. Packets sent over a switch interface can be dropped in several ways, as described in the following sections.

5.12.1Packets dropped because of a software problem on an endpoint

Packets are sometimes dropped at one of the endpoints of the packet transfer. In this case, you should be able to run AIX 5L commands to see some evidence on the endpoint that dropped the packet. For example, run /usr/sni/sni.snap -l {adapter_number} to get the correct endpoint data. This is best taken both before and after re-creating the problem. The sni.snap creates a new archive in /var/adm/sni/snaps. For example, /usr/sni/sni.snap -

l1 produces a hostname.adapter_no.timestamp file such as /var/adm/sni/snaps/c704f2n01.1.041118122825.FEFE5.sni.snap.tar.Z.

For IP traffic, looking at netstat -Ddata is a good place to start:

netstat -D
Source	Ipkts	Opkts	Idrops	Odrops
[. . .]
sn_dmx0	156495	N/A	0	N/A
sn_dmx1	243602	N/A	0	N/A
sn_if0	156495	140693	0	0
sn_if1	243602	241028	0	13
ml_if0	0	98	0	10

The ifsn_dump command provides interface-layer statistics for the sni interfaces. This tool helps you diagnose packet drops seen in netstat -Dand also prints some drops that are not shown under netstat.

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