SAP HANA does not use vPMEM DAX in memory database
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SUSE Linux Enterprise Server for SAP 15
SUSE Linux Enterprise Server HPC
Systems using DAX in memory filesystems, such as Intel Optane memory.
root@geeko:/root# df -BG | grep pmem /dev/pmem0 269G 268G 2G 100% /hana/pmem/pmem0 /dev/pmem1 757G 2G 756G 1% /hana/pmem/pmem1 /dev/pmem2 373G 1G 372G 1% /hana/pmem/pmem2 /dev/pmem3 403G 1G 402G 1% /hana/pmem/pmem3 /dev/pmem4 394G 386G 9G 98% /hana/pmem/pmem4 /dev/pmem5 596G 592G 5G 100% /hana/pmem/pmem5 /dev/pmem6 405G 398G 8G 99% /hana/pmem/pmem6
See if the output of:
for the mountpoint contains 'dax' as an option. If it does not add it to the mount options in fstab and remount the filesystem.
Also make sure that the xfs filesystem does not have the reflink option enabled. This is enabled implicitly by default during filesystem creation. The default crc=1 global metadata option will imply reflink=1
This can be option can be disabled only during filesystem creation.
XFS filesystems must not have the reflink option enabled.
There are other reasons why HANA might not be able to use the in memory filesystem. These are the two most common ones.
Kernel documentation can be found here:
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- Document ID:000020271
- Creation Date: 04-Jun-2021
- Modified Date:02-Jul-2021
- SUSE Linux Enterprise Server
- SUSE Linux Enterprise Server for SAP Applications
- SUSE Linux Enterprise HPC
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