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SAP HANA

SAP HANA TDI on Cisco UCS and VMware vSphere - Part 4

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Guest Operating System

Installation

The installation of the Linux OS has to be done according to the SAP Notes for HANA systems on SLES or RHEL. The network and storage configuration parts are heavily depending on the TDI landscape, therefore no general advice can be given.

Disk Distribution

The VMDKs should be distributed on differently tiered storage systems because of performance reasons. Example:

In the end, a realistic storage quality classification as well as a thorough distribution of the disks among datastores and virtual SCSI adapters ensures good disk IO performance for the HANA instance.

Configuration

With regards to the network configuration, it is not recommended to configure bond devices inside the Linux guest OS. Such a configuration is used in native environments to guarantee availability of the network adapters. In virtual environments, the redundant uplinks of the vSwitch take on that role.

In /etc/sysctl.conf some tuning might be necessary for scale-out and in-guest NFS scenarios:

net.ipv4.tcp_slow_start_after_idle = 0

net.core.rmem_max = 16777216

net.core.wmem_max = 16777216

net.core.rmem_default = 262144

net.core.wmem_default = 262144

net.core.optmem_max = 16777216

net.core.netdev_max_backlog = 300000

net.ipv4.tcp_rmem = 65536 262144 16777216

net.ipv4.tcp_wmem = 65536 262144 16777216

net.ipv4.tcp_no_metrics_save = 1

net.ipv4.tcp_moderate_rcvbuf = 1

net.ipv4.tcp_window_scaling = 1

net.ipv4.tcp_timestamps = 1

net.ipv4.tcp_sack = 1

sunrpc.tcp_slot_table_entries = 128

MANDATORY:

Validation

To validate the solution, the same hardware configuration check tool as for the appliances is used but with slightly different KPIs. SAP supports performance-related SAP HANA issues only if the installed solution has passed the validation test successfully.

Volume

Block Sizes

Test File Size

KPIs

Initial Write (MB/s)

Overwrite (MB/s)

Read (MB/s)

Latency (┬Ás)

Log

4K

5G

-

30

-

1000

16K

16G

-

120

-

1000

1M

16G

-

250

250

-

Data

4K

5G

-

-

-

-

16K

16G

40

100

-

-

64K

16G

100

150

250

-

1M

16G

150

200

300

-

16M

16G

200

250

400

-

64M

16G

200

250

400

-

Source: SAP SE, Version 1.8

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Part 1 - Introduction

Part 2 - ESXi Host

Part 3 - Virtual Machine

Part 4 - Guest Operating System

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