setting RAID driver options on bootup

["Tom Metro-12" <user=71@nabble.blu.org>]

 On an Ubuntu Fiesty system I'm attempting to set some custom md driver 
(RAID) setting via /etc/sysctl.conf: 

   dev.raid.speed_limit_min = 100 

but on bootup it reports that it doesn't recognize 
dev.raid.speed_limit_min (and the setting doesn't change), although this 
command: 

   # sysctl -a | fgrep -i raid 
   dev.raid.speed_limit_max = 200000 
   dev.raid.speed_limit_min = 1000 

shows that it knows that variable, and running this: 

   # sysctl -p /etc/sysctl.conf 
   kernel.printk = 4 4 1 7 
   dev.raid.speed_limit_min = 100 

produces no error. 

I'm wondering if it is a timing issue, as the system doesn't boot using 
md, so perhaps the module is being loaded after sysctl is ran? (And I'm 
assuming the kernel passes on these variables to the various modules to 
consume.) 

This should only explain it if the RAID driver is dynamically loaded, 
rather than compiled-in. According to: 

# fgrep -i raid /boot/config-`uname -r` 
CONFIG_RAID_ATTRS=m 
CONFIG_BLK_DEV_3W_XXXX_RAID=m 
CONFIG_SCSI_AACRAID=m 
CONFIG_MEGARAID_NEWGEN=y 
CONFIG_MEGARAID_MM=m 
CONFIG_MEGARAID_MAILBOX=m 
CONFIG_MEGARAID_LEGACY=m 
CONFIG_MEGARAID_SAS=m 
# Multi-device support (RAID and LVM) 
CONFIG_MD_RAID0=m 
CONFIG_MD_RAID1=m 
CONFIG_MD_RAID10=m 
CONFIG_MD_RAID456=m 
CONFIG_MD_RAID5_RESHAPE=y 

it looks like it is dynamically loaded. 

The only reference I see to "raid" or "md" in /etc/modules or 
/etc/modprobe.d/ is: 
alias block-major-9-*  md 

in /etc/modprobe.d/aliases. Perhaps a Udev hook might be the place to 
make the sysctl call. 

Anyone know of a good fix for this, aside from the obvious hack of 
putting a sysctl call in rc.local or similar? 

Could this be accomplished with an options line in a file under 
/etc/modprobe.d/? 

  -Tom 

-- 
Tom Metro 
Venture Logic, Newton, MA, USA 
"Enterprise solutions through open source." 
Professional Profile: http://tmetro.venturelogic.com/

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