dd conv=fdatasync , oflag=direct , oflag=dsync

P

postcd

Guest
Please kindly what is the difference between following 3 "dd" parameters?

1) conv=fdatasync
2) oflag=direct
3) oflag=dsync


[[email protected]* *]# dd bs=1M count=256 if=/dev/zero of=test conv=fdatasync
256+0 records in
256+0 records out
268435456 bytes (268 MB) copied, 7.64957 seconds, 35.1 MB/s

[[email protected]* *]# dd bs=64k count=3200 if=/dev/zero of=test oflag=direct;
3200+0 records in
3200+0 records out
209715200 bytes (210 MB) copied, 6.28575 seconds, 33.4 MB/s

[[email protected]* *]# dd bs=1M count=256 if=/dev/zero of=test oflag=dsync
256+0 records in
256+0 records out
268435456 bytes (268 MB) copied, 70.6569 seconds, 3.8 MB/s
 


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