View Full Version : [ubuntu] Samsung 840 Pro 128GB | Asus U36JC slow speed?

December 31st, 2012, 10:07 PM
I just installed Elementary OS (Ubuntu 12.04 based) on my Samsung 840 Pro (128GB) using GPT and aligned all the partitions. After installing Ubuntu, I modified the Fstab to add noatime and discard.

The strange thing that i'm noticing when I run hdparm -Tt is how slow the cached read and disk reads:

Timing cached reads: 6290 MB in 2.00 seconds = 3145.90 MB/sec
Timing buffered disk reads: 754 MB in 3.01 seconds = 250.81 MB/sec

Which is odd since I saw hdparm results for the Samsung 830 on archlinux:

# hdparm -Tt /dev/sda
Timing cached reads: 22130 MB in 2.00 seconds = 11080.54 MB/sec
Timing buffered disk reads: 1500 MB in 3.00 seconds = 499.38 MB/sec

Anyone know what could be causing this?

January 10th, 2013, 03:00 AM
A) That's pretty fast still! Compared to a platter drive you're flying :D

B) My google search shows that your computer has SATA II, which is limiting the speeds to about 300 MB/s. Only with a SATA III compatible machine will you hit the speeds close to 600 MB/s.

See http://en.wikipedia.org/wiki/Serial_ATA