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Slow solid state drive on laptop running Linux


I installed a solid state drive on my laptop, but I don't get the blazing speeds which people write about.


My system:



  • Laptop: Acer Aspire 7552G-6061

  • Solid state drive: Crucial 256GB M4 CT256M4SSD2

  • Operating system: Linux (Trisquel 5.5, a derivative of Ubuntu)


I am using AHCI.


I installed the operating system onto the solid state drive (as opposed to copying it).


How can I make the solid state drive faster? Could the problem be with the block or sector alignment?



Answer



Answering Your Questions First



  • The problem should not be related to sector alignment.

  • I have two tips below for keeping up performance on SSDs.


Understanding SSD Benefits


The "blazing speeds" people experience on solid-state drives are referring to reading from and writing to the drive. Compared to hard disk drives, SSDs have very low access times and higher data transfer rates, especially when accessing randomly.


Operations beyond reading and writing data to the SSD do not have a performance increase, such as using the processor to make intensive calculations. If your expectation from your SSD is to have performance improvements for CPU or RAM operations, this is why you aren't getting the "blazing speeds".


Did you notice your boot time decrease dramatically transitioning from an HDD to an SSD? I used to be frustrated at my laptop for taking over 50 seconds to boot. Now, with my own Crucial 256GB m4 CT256M4SSD2, my laptop boots in no more than 12 seconds (and this includes running a full LAMP server!)


When a computer is booting from an HDD, files have to be read from different physical locations. The seek time of the reading head moving to the next location is a huge performance killer. The Crucial m4 has an average access time of 0.1 ms. The hard drive I had before (a Toshiba MK6461GSYN) has an average access time of 15.8 ms. Not only is the SSD much faster, it also reads and writes over twice as fast (240+ MB/s) as my HDD can (120 MB/s maximum).


If you haven't experienced a huge decrease in boot time, I can't guess why from the information you provided. To some people who are wondering why I haven't suggested TRIM, it's because TRIM isn't relevant yet. TRIM is only useful for writing to the SSD, but booting an operating system is primarily reading.


Improving SSD Performance on Linux


There are only two things that I recommend.



  1. Enabling TRIM

  2. Setting noatime


Enabling TRIM


TRIM keeps the write performance of your SSD like-new by telling the SSD what sectors are no longer in use and thus, reducing write amplification.


In a terminal, run the command sudo nano /etc/fstab.


Use the arrow keys and find the entry or entries that are partitions on your SSD. For each entry, add discard to the options. A line may look something like this afterwards:


UUID=ed586ab8-08c5-4bae-b118-d191b716b4a4 /               ext4    discard,errors=remount-ro 0       1

Skip to the section below to apply noatime as well, or press CtrlX, type Y, then press Enter to save the changes.


Setting noatime


noatime tells the filesystem not to write to files when they were last accessed. Logging latest access times, in most cases, is not necessary and is a waste of effort on both SSDs and HDDs.


Like the section above, make sure that you've run the command sudo nano /etc/fstab and are in the nano text editor.


Use the arrow keys and find the entry or entries that are partitions on your SSD. For each entry, add noatime to the options. A line may look something like this afterwards:


UUID=ed586ab8-08c5-4bae-b118-d191b716b4a4 /               ext4    noatime,discard,errors=remount-ro 0       1

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