Could you please help me to understand 'direct-io-mode' in GlusterFS.
I'm getting better read results with direct I/O mode disabled - is it mean that in disabled mode it's writing/reading from cache - is it a system cache or GlusterFS cache? What's the recommended method? I'm using 4 nodes with distributed-replicated volume for web serving:
Write: dd if=/dev/zero of=tempfile bs=1M count=1024 conv=fdatasync,notrunc echo 3 > /proc/sys/vm/drop_caches Read: dd if=tempfile of=/dev/null bs=1M count=1024 Read-Read: dd if=tempfile of=/dev/null bs=1M count=1024 Write Read Re-Read 67.5 MB/s 94.9 MB/s 94.6 MB/s direct-io-mode=enabled 65.8 MB/s 230 MB/s 226 MB/s direct-io-mode=disabled