Subject: POOR SSA DISK WRITE PERFORMANCE
New Netfinity server RETAIN Tip:
Record number: H166560
Hit count: UHC00000
Success count: USC0000
Publication code: PC50
Date created: O99/05/05
Date last altered: A99/05/21
Owning B.U.: USA
Abstract: POOR SSA DISK WRITE PERFORMANCE
Poor SSA Disk write performance on Netfinity 7000 server or PC Server 704.
A performance degradation has been found on the Netfinity 7000 and PC Server 704 with respect to specific placement of PCI adapter cards.
The problem was originally found while performing a network based restore to SSA disk drives.
Any load where both disk and network traffic are occurring simultaneously would be affected.
The problem is caused by PCI Slot restrictions on the Netfinity 7000 and PC Server 704.
The degradation occurs when both conditions 1 and 2 are met:
Further degradation may occur if both conditions 1 and 2 (above) are met, accompanied by either condition 3 or 4:
PROBLEM ISOLATION AIDS:
a Netfinity 7000 server, Type 8651, any Model.
a PC Server 704, Type 8650, any Model.
IBM SSA RAID Adapter for PC Servers, Option P/N 32H3811
IBM SSA RAID Cluster Adapter for PC Servers, Option P/N 96H9835
IBM SerialRAID Adapter for PC Servers, Option P/N 09L2084
IBM Advanced SerialRAID/X Adapter for PC Servers, Option P/N 09L2123
Any Network Adapter
OS/2 versions 3.0 or 4.0 at any fix pack level
NetWare version 4.11 at any patch level
NT versions 3.51 or 4.0 at any service pack level
The SSA adapter in PCI slot-1 or slot-6 will be affected by a High Performance PCI adapter in either of the two remaining slots of the respective PCI bus.
The SSA adapter will also be affected if the High Performance adapter is in slot-1 or slot-6 and the SSA adapter is on the same bus.
Lab tests have shown that the IBM EtherJet Adapter and the IBM ServeRAID adapter are two examples of "High Performance" adapters.
The sensitivity to slot-1 and slot-6 led to recommended slot placement of adapters.
Note: Three (3) of the same type of adapters on one bus (e.g. three (3) SSA adapters in slots 1, 2, and 3) do not exhibit this problem.
Netfinity 7000 and PC Server 704 Slot to Bus Mapping:
Slot Number Bus Number
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