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- Memory Mode: The Apache Pass/Optane Memory is exposed as RAM to the OS. Although the hardware is different, this mode allows transparent usage of this memory type. The main benefits are the gained memory capacity and easy usage (no modification of applications required). The DRAM memory acts as cache for Optane Memory. In this mode, the SCM is effectively not persistent.
- AppDirect Mode: The Apache Pass/Optane Memory is exposed as block device(s) to the OS (usually as /dev/pmemX, depending on actual configuration). On such block devices, a file system can be created which should support the direct access (DAX) option. This enables mapping data on the persistent Optane Memory into an application's virtual address space while avoiding the OS' page cache. Thus, direct media access with load/store operations is possible. Note that data on the Optane Memory is deleted when the mode is changed. Therefore, data on /dev/pmem should be considered as ephemeral.
- (Mixed/Hybrid Mode: The System can also be configured to provide a portion of the Optane capacity for the Memory Mode and another portion for AppDirect mode.)
By default: apass1 is configured in Memory Mode while apass2 is configured in AppDirect Mode. (tbd) If you need a different configuration contact ...who....
As simple check for the given mode you can run free -h. If the total memory capacity is around or larger than 3 TB the system is in memory mode. Further, if /dev/pmem[01] exists, the AppDirect (or Mixed/Hybrid) mode is in effect.
hostname: apass{1,2}.xxxxx
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