Problems with Velox SSD cache and O_DIRECT

[sumokiama]

Given the Velox configuration:
enable-ssd-cache=true
memory-use-mmap=true
cache.ssd-enable-odirect=true

Velox is sending misaligned data to the SSD cache and the device throws errors:
E1107 19:53:48.763626 87470 SsdFile.cpp:446] [SSDCA] Failed to write to SSD, file name: /mnt2/ssd/velox20, size: 3, offset: 2548736256, error code: 22, error string: Invalid argument

Assuming there is no way that O_DIRECT can be made compatible with misaligned data, is there a way in Velox via configuration to ensure alignment (in this case the drive has a 4KB blocksize)?

[majetideepak]

Unfortunately, there is no config to get aligned writes. The recommendation is to disable O_DIRECT. Apart from unaligned writes, some filesystems such as btrfs have consistency bugs when O_DIRECT is set in some kernel versions.