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Determining Disk Speed

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Old 10-04-2012
mojoman mojoman is offline
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Determining Disk Speed

Hi,

I went to a computer store and the salesman sold me a SATA cable and told me that all SATA cables are the same. Another salesman at a different store told me a cable rated for SATA 2, which I bought, MIGHT work as well as one rate for SATA 3 but it is not guaranteed. I decided to run a speed test on my SSD drive to check the results.


Code:
dd if=/dev/zero of=/tmp/output.img bs=8k count=256k
262144+0 records in
262144+0 records out
2147483648 bytes (2.1 GB) copied, 0.530362 s, 4.0 GB/s




Code:
for i in 1 2 3; do hdparm -tT /dev/sda; done

/dev/sda:
 Timing cached reads:   27076 MB in  2.00 seconds = 13556.06 MB/sec
 Timing buffered disk reads: 1244 MB in  3.00 seconds = 414.46 MB/sec

/dev/sda:
 Timing cached reads:   28788 MB in  2.00 seconds = 14414.45 MB/sec
 Timing buffered disk reads: 1244 MB in  3.00 seconds = 414.48 MB/sec

/dev/sda:
 Timing cached reads:   27958 MB in  2.00 seconds = 13998.11 MB/sec
 Timing buffered disk reads: 1248 MB in  3.00 seconds = 415.91 MB/sec
[root@mohit-speed-daemon ~]#

I can verify from dmesg and /var/log/messages analysis that I am connected a 6.0gbps. Are my results consistent with that type of connection?
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Old 10-04-2012
rdrtx1 rdrtx1 is offline
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Code:
sudo hdparm -I /dev/sda | grep -i speed

where /dev/sda : Hard disk device file
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Old 10-04-2012
mojoman mojoman is offline
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That command will just tell me that these speeds are supported.
I ran the read/write tests to see what speed it is actually operating at.
I want to know if these speeds are acceptable for a 6.0gbps drive?
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Old 10-05-2012
Corona688 Corona688 is offline Forum Staff  
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The maximum transfer rate of SATA 2 is, ideally, around 300 megabytes per second. You're beating that by 30% in the real world so it really does look like you're getting SATA 3 speeds.

Just because a drive uses a SATA 3 port doesn't mean it's capable of its full 600 megabytes per second, of course. Whether you're reaching the true maximum speed of your drive, I can't say without knowing what it is and looking in its manual. The limits of your southbridge and memory are also important.

Last edited by Corona688; 10-05-2012 at 12:22 PM..
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