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Confused about DISK IO (direct, dsync and fdatasync)
bdwebservices
Member
Hello,
This is my server. I did 3 benchmark. Which one is real DISK IO and which one I have to consider to use as shared hosting server?
[root@srv ~]# dd if=/dev/zero of=test bs=1M count=1024 oflag=dsync && rm -f test
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 3.43017 s, 313 MB/s
[root@srv ~]# dd if=/dev/zero of=test bs=1M count=1024 oflag=direct && rm -f test
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 1.16952 s, 918 MB/s
[root@srv ~]# dd if=/dev/zero of=test bs=1M count=1024 conv=fdatasync && rm -f test
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 2.49561 s, 430 MB/s
Thanks,
Comments
Try checking this @rm_'s site for more explanation please: DD Benchmarking
He explains it better than I now can and is the first result to my search. So.. (: