Hi,
        after doing the "dd" tests for a server we have at work I obtained:
Read: 47.20 Mb/s
Write: 39.82 Mb/s
        Some days ago read performance was around 20Mb/s due to no readahead in 
md0 
so I modified it using hdparm. However, it seems to me that being it a RAID1 
read speed could be much better. These are SATA disks with 3Gb of RAM so I 
did 'time bash -c "dd if=/dev/zero of=bigfile bs=8k count=786432 && sync"'. 
File system is ext3 (if read many times in the list that XFS is faster), but 
I don't want to change the file system right now. Modifing the readahead from 
the current 1024k to 2048k doesn't make any difference. Are there any other 
tweaks I can make?
 

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