Saltstack : state for SDCard / flash storage optimization (Arm SBC)
All my servers are small Arm SBCs that use SDCards or eMMC for storage. For all of them, I use the same optimization state that basically do 2 things :
- Change commit and barrier settings of ext4 (with a proper backup-ed power system)
- Set the scheduler to deadline, which is the more efficient one for my usage
The state:
# define sdcard optimized mounting option for root fs on sdcards or emm flash/:mount.mounted:
- device: {{ grains['rootfs'] }}
- fstype: ext4
- opts: defaults,async,barrier=0,commit=100,noatime,nodiratime,errors=remount-ro
- dump: 0- pass_num: 1# set default IO sceduler to deadline for sdcard# deadline scheduler could group small accesses to lesser sdcard latency/etc/udev/rules.d/60-schedulers.rules:
file.managed:
- source: salt://sdcard_optim/60-schedulers.rules
- user: root
- group: root
- mode: 644
As you can see, I use a custom grains to determine the root partition, because I have several servers with different configurations.
Here is my “rootfs” grains, stored in <salt home>/states/base/_grains/rootfs.py:
#!/usr/bin/pythonimport subprocess
def function():
'''Return the rootfs partition'''grains = {}
command = ('df -h | grep \'\/$\' | awk \'{ print $1 }\'')
p = subprocess.Popen(command, universal_newlines=True,shell=True, stdout=subprocess.PIPE,stderr=subprocess.PIPE)
grains['rootfs'] = p.stdout.read()
retcode = p.wait()
return grains
The “60-schedulers.rules” files is a simple udev order to force the deadline scheduler on all SDCards :
# set deadline scheduler for sdcard ACTION=="add|change", KERNEL=="mmcblk[0-9]", ATTR{queue/scheduler}="deadline"
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