Application Notes: eMMC lifetime optimization - Revision history

imported>Uri.mashiach: /* Do not use swap space */

2021-01-26T08:34:19Z

‎Do not use swap space

imported>Uri.mashiach at 15:34, 7 October 2020

2020-10-07T15:34:31Z

imported>Igor.vaisbein at 12:22, 8 September 2019

2019-09-08T12:22:17Z

imported>Igor.vaisbein: Igor.vaisbein moved page Application Notes: eMMC endurance to Application Notes: eMMC lifetime optimization

2019-06-12T14:10:19Z

Igor.vaisbein moved page Application Notes: eMMC endurance to Application Notes: eMMC lifetime optimization

New page

==Introduction==

Flash memory devices have limited endurance that is measured in program-erase (P/E) cycles. P/E cycle is a sequence of events in which data is written to solid-state flash memory cell, then erased, and then rewritten. Typical eMMC endurance is 3000 P/E cycles. Problems with storage can negatively affect performance and reliability of the device. It is highly important to take into consideration eMMC endurance during embedded system development.
Standard operating systems and file-systems typically are not configured for eMMC lifetime optimization. It is recommended to employ the techniques outlined below in order to configure the system for optimized eMMC usage.

==Recommendations for eMMC lifetime optimization==

===Use tmpfs===
Use tmpfs to store temporary files. Tmpfs is a temporary file storage facility on Unix-like systems stored in RAM. It helps to reduce unnecessary writes to the eMMC.</br>
To mount temporary directories as tmpfs add the following entries into the system '''/etf/fstab''':
<pre>
tmpfs /tmp tmpfs defaults,noatime,mode=1777 0 0
tmpfs /var/tmp tmpfs defaults,noatime,mode=1777 0 0
</pre>

===Turn off logging===
Turn off or reduce logging. Writing or removing big amounts of data on a regular basis significantly decreases eMMC lifetime.<br>
Turning off the syslog on boot should be done with following command:
<pre>
systemctl disable syslog
</pre>

To mount logging as tmpfs add the following entry into the system '''/etf/fstab''':
<pre>
tmpfs 100M 596K 100M 1% /var/log
</pre>

Turn off logging of read access times. To do this add the following entry into the system '''/etf/fstab''':
<pre>
/dev/sdxxxxxx / ext4 discard,noatime,errors=remount-ro 0 1
</pre>

===Do not use swap space===

Do not use swap space. Swapping uses internal storage intensively and should be minimized or disabled to increase eMMC lifetime.

Decreasing swap usage should be done with following command:
<pre>
vm.swappiness=10
</pre>

Disabling swap usage should be done with following command:
<pre>
vm.swappiness=0
</pre>

===Use SquashFS===
SquashFS is a compressed file-system that is intended for read-only usage.

[[Category:Linux]]
[[Category:Yocto]]

@@ Line 23: / Line 23: @@
 To mount logging as tmpfs add the following entry into the system '''/etc/fstab''':
 <pre>
-tmpfs   100M  596K  100M   1% /var/log
+tmpfs      /var/log            tmpfs      defaults,size=128M     0  0
 </pre>
-Turn off logging of read access times. To do this add the following entry into the system '''/etc/fstab''':
+Turn off logging of read access times, by adding the '''noatime''' option to the rootfs line, in the '''/etc/fstab'''<br>
 <pre>
-/dev/sdxxxxxx / ext4 discard,noatime,errors=remount-ro 0 1
+/dev/root  /                   auto       defaults,noatime      1  1
 </pre>

@@ Line 14: / Line 14: @@
 </pre>
-===Turn off logging===
+===Turn off logging - Legacy Systems===
 Turn off or reduce logging. Writing or removing big amounts of data on a regular basis significantly decreases eMMC lifetime.<br>
 Turning off the syslog on boot should be done with following command:
@@ Line 38: / Line 38: @@
 Decreasing swap usage should be done with following command:
 <pre>
-vm.swappiness=10
+sysctl vm.swappiness=10
 </pre>
 Disabling swap usage should be done with following command:
 <pre>
 vm.swappiness=0

@@ Line 8: / Line 8: @@
 ===Use tmpfs===
 Use tmpfs to store temporary files. Tmpfs is a temporary file storage facility on Unix-like systems stored in RAM. It helps to reduce unnecessary writes to the eMMC.</br>
-To mount temporary directories as tmpfs add the following entries into the system '''/etf/fstab''':
+To mount temporary directories as tmpfs add the following entries into the system '''/etc/fstab''':
 <pre>
 tmpfs   /tmp       tmpfs   defaults,noatime,mode=1777   0 0
@@ Line 21: / Line 21: @@
 </pre>
-To mount logging as tmpfs add the following entry into the system '''/etf/fstab''':
+To mount logging as tmpfs add the following entry into the system '''/etc/fstab''':
 <pre>
 tmpfs   100M  596K  100M   1% /var/log
 </pre>
-Turn off logging of read access times. To do this add the following entry into the system '''/etf/fstab''':
+Turn off logging of read access times. To do this add the following entry into the system '''/etc/fstab''':
 <pre>
 /dev/sdxxxxxx / ext4 discard,noatime,errors=remount-ro 0 1