Smartctl : Linux disk I/O scheduler is reseted back to default's CFQ

Got a weird issue recently, I'm monitoring my SSD's life time with smartctl + Zabbix and realized that my scheduler settings are reseted each time smartctl was executed !

 # echo noop > /sys/block/sda/queue/scheduler  
   
 # cat /sys/block/sda/queue/scheduler  
 [noop] anticipatory deadline cfq  
   
 # smartctl -A --device=sat+megaraid,0 /dev/sda  
 smartctl 5.43 2012-06-30 r3573 [x86_64-linux-2.6.32-358.23.2.el6.x86_64] (local build)  
 Copyright (C) 2002-12 by Bruce Allen, http://smartmontools.sourceforge.net  
 === START OF READ SMART DATA SECTION ===  
 ...  
 ...  
   
 # cat /sys/block/sda/queue/scheduler  
 noop anticipatory deadline [cfq]  

There is no real solution, but you can work around by specifying  the generic SCSI name i.e "sgX "instead of sdX.

 # echo noop > /sys/block/sda/queue/scheduler  
   
 # cat /sys/block/sda/queue/scheduler  
 [noop] anticipatory deadline cfq  
   
 # smartctl -A --device=sat+megaraid,0 /dev/sg0  
 smartctl 5.43 2012-06-30 r3573 [x86_64-linux-2.6.32-358.23.2.el6.x86_64] (local build)  
 Copyright (C) 2002-12 by Bruce Allen, http://smartmontools.sourceforge.net  
 === START OF READ SMART DATA SECTION ===  
 ...  
 ...  
   
 # cat /sys/block/sda/queue/scheduler  
  [noop] anticipatory deadline cfq 

And voila ! Problem not really solved but that does the job !

You can use sg_map (part of the sg3_utils package) to check the sdX -> sgX mappings :

 # sg_map -a  
 /dev/sg0 /dev/sda  
 /dev/sg1 /dev/sdb  
 /dev/sg2 /dev/scd0