20 Issue 1404

In a terminal, type:

sudo nano /etc/cron.daily/fstrim

Use the cursor keys to move around, backspace or delete to edit
lines, and Ctrl+o to save, followed by Ctrl+X to exit.
Edit the line that starts ‘exec fstrim-all’ toread ‘exec fstrim-all –
no-model-check’.
This method is to be preferred to setting dynamic trim by adding
the discard option in fstab entries, which can cause slowdown on
current kernels.

PreventDatestamping
atime is the access time option. When enabled, this means that the
datestamp on each file is updated every time it is accessed, which
adds to unwanted writes. It can be disabled by editing the /etc/fstab
file entry for the SSD.
Toedit the /etc/fstab file, first back up the fstab file in case of
problems, using the following command:

cp /etc/fstab /etc/fstab.bak

Then to edit it:

sudo nano /etc/fstab

Now, make the following changes to each SSD drive entry.
If relatime is present,remove it, and add noatime. The entries
may look like this:

/dev/sda1 / ext4 relatime,errors=remount-ro
0 1

...or this:

/ was on /dev/sda1 during installation

UUID=77d591aa-23d0-4470-9c67-06295454be7a /
ext4 relatime,errors=remount-ro 0 1

Either way, edit the options separated by commas like this:

noatime,errors=remount-ro 0 1

MoveSystemCacheTo RAM
While we’re looking at the fstab file, there’s another change that
can be made. The system cache is stored in /tmp, which is inroot.
By default, this is flushed on every boot. If you have 4GB or more
of RAM, it can be moved to RAM, whichreduces disk writes and
improves access times.
Add this line to the bottom of the fstab:

tmpfs /tmp tmpfs defaults,noatime,mode=1777 0 0

Save the fstab file andreboot to apply these changes.

SSDs:AShortGuide

SSDs have changed immensely over the last few years. For

example, ‘wear levelling’ ensures that writes are applied

evenly over the memory cells, and initial problems with

drive partitioning and operating system incompatibilities

have been overcome. Prices have dropped steadily, while

capacity has increased.

Of course, what follows is grossly simplified, and there

are many other factors that can affect performance and

longevity. As the market develops, new ways of optimising

memory cells are emerging. Firmware in controllers and

software in operating systems continues to improve, as do

manufacturing processes.

There are currently three main types of SSD: SLC, MLC

and TLC.

SLC

These are single-level cell devices, which means they

store one bit of data per memory cell. This gives higher

sequential and random data read and write speeds, faster

access times and a longer life for the device, as they can

tolerate a larger number of write operations. This comes

at a cost, however, which means they’re mainly used for

enterprise applications in servers.

MLC

MLC stands for multi-level cell. Most SSDs sold for general

use are MLC. In these devices, the voltage output level

of each cell can be used to represent more than one bit,

enabling it to store two bits per cell. This reduces the

manufacturing costs but slightly reduces read/write speeds

and increases access time. The life of an MLC device is

roughly two thirds of that of an SLC device, which is still

about four times that of a typical mechanical hard drive.

TLC

TLC devices use triple-level cells, which reduces the price

further, but at the cost of lower speeds and a shorter life.

Mixing It Up

In addition to these basic forms, hybrid devices use a mix

of these three types of memory cells.

SLC SSDs have cells that can be flipped between SLC

and MLC modes depending on storage requirements,

essentially operating as SLC until the drive starts to fill

up past the 50% mark. This increases speed and lifespan,

while still keeping the costs down. These are often used

for embedded applications, such as in printers, where the

full capacity is seldom used. I purchased one of these,

which was ideal for my choice of OS.

There are other types of hybrids emerging. For example,

some use SLC for a high-speed cache and TLC for longer-

term storage.

Other types of solid-state memory worth mentioning

are SD cards and eMMC (Embedded MultiMediaCard).

Most phones, tablets, and Chromebooks (including

convertibles often sold as laptop replacements) use

eMMC modules for storage. They’re more like SD card

memory than a true SSD. Although they’re faster thana

mechanical drive, SD cards are slower than a true SSD and

are not as well suited to the frequent write cycles ofa

typical PC.

Even a standard Linux

distro can easily fit in 8GB

or less



