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 direct instructions can be given.
In this example, 5 vmdk based disks are used as already mentioned in Part 3.
The figure above shows that the order of the disks does not necessarily reflect the order in the VM configuration. Ensure that the mapping between the disks and mount points is correct. Labeling disk partitions (and mounting via labels) rather than using potentially rearranged SCSI device names (/dev/sd*) or potentially changing ID's (/dev/disk/by-id resp. /dev/disk/by-uuid) helps avoiding confusion.
Here is an example of the /etc/fstab:
LABEL=root / ext3 defaults 0 1
LABEL=hanashared /hana/shared ext3 defaults 0 0
LABEL=hanadata /hana/data ext3 defaults 0 0
LABEL=hanalog /hana/log ext3 defaults 0 0
LABEL=backup /backup ext3 defaults 0 0
Disk distribution and mount point overview
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.
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.
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 (MB/s) | Latency | ||
Initial Write | Overwrite | Read | µs | |||
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 AG, Version 1.3.0
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