Experimenting with ASM Filter Drivers

Oracle is moving away from ASMlib, and introducing ASM Filter Drivers as a replacement.

ASM Filter Drivers will handle consistent device naming and permissions, as well as filter out illegal IO to ASM devices to protect against rogue dd commands corrupting ASM disks.

Future plans include support for TRIM commands to enable thinly provisioned disks to reclaim deleted blocks without having to resort to the massively dangerous ASRU tool.

ASM Filter Drivers were introduced with Oracle 12.1.0.2, but the implementation is currently one massive kludge.  By default on 12.1.0.2, OEL7 is not supported without a patch (patch 21053000).  OEL6 UEK is also not supported without a patch (patch 18321597).

Note that the patches require OPatch 12.1.0.2, but Oracle Grid Infrastructrue 12.1.0.2 installs OPatch 12.1.0.1.3 so you have to patch the patcher (patch 6880880), so you can patch the Oracle software, to make Oracle ASM Filter Drivers work with Oracle’s own operating system kernel.  Clear?  Good!

You cannot install Filter Drivers by default.  You have to migrate to them from UDEV or ASMlib.

Oracle 12.2 should hopefully fix this mess and make Filter Drivers actually usable, but in the meantime it might be fun to play with the new technology and see what it can do.

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