??????????????????????????????????????IO????????????ж???IO?????????????????ò????????????????.??????????????????????д????????????????????.
??????????????????????
????(1)???hdparm????
????????????????????ATA/IDE?????????????????????Linux IDE????????????????? Mark Lord??????д??( hdparm has been written by Mark Lord <mlord@pobox.com>?? the primary developer and maintainer of the (E)IDE driver for Linux?? with suggestions from many netfolk).?????????????????Linux????????UNIX????ATA/IDE????????????????????????????????????е?.
??????÷??????
# hdparm -Tt /dev/sda
/dev/sda:
Timing cached reads: 6676 MB in 2.00 seconds = 3340.18 MB/sec
Timing buffered disk reads: 218 MB in 3.11 seconds = 70.11 MB/sec
?????????????2????????6676MB????棬???3340.18 MB/sec;
??????3.11???ж????218MB????(?????)???????????70.11 MB/sec
????(2)???dd????
?????????????????????????????????????????????????????????????????????????д????????????????.
?????????????????????????????????×NIX??????а????????Oracle???豸?????????dd?????????.
??????????????????????????豸
????/dev/null α?豸???????.д????????????IO
????/dev/zero α?豸???????????????????????????IO
???????????:
????a.????????IOд???
# time dd if=/dev/zero of=/test.dbf bs=8k count=300000
300000+0 records in
300000+0 records out
10.59s real 0.43s user 9.40s system
# du -sm /test.dbf
2347 /test.dbf
???????????????10.59????????????2347M??????????IOд???????221.6MB/sec;
???????????????????????????????????????????.
????b.????????IO?????
# df -m
Filesystem 1M-blocks Used Available Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
19214 9545 8693 53% /
/dev/sda1 99 13 82 14% /boot
none 506 0 506 0% /dev/shm
# time dd if=/dev/mapper/VolGroup00-LogVol00 of=/dev/null bs=8k
2498560+0 records in
2498560+0 records out
247.99s real 1.92s user 48.64s system
???????????????247.99????????????19214MB??????????????????????77.48MB/sec