megaraid causing high-load

David Lucas dlucas at
Tue Mar 8 21:38:43 CST 2005

I am having some difficulty with the megaraid drivers in a PowerEdge 
with a CERC ATA100/4ch.  The write speed is notoriously slow and it 
causes a high load (which jumps up to 5-20) with very little 
corresponding CPU usage (via top).  The responsivity of the system then 
becomes very sluggish and I have been having some errors with the 
filesystem (Reiserfs) which then has caused the system to hang on 
several occasions.  I am using a single RAID 5 partition ... 228Gb in total.

The load never really drops low ... always hovering around the 0.10-0.40 
mark even when the system is barely idle.

I have scoured the mailing lists and the web and have not come up with 
any real solutions. The system has 1Mb of memory, and I have turned the 
swap off with little to no effect.  The system is barely used, yet 
suffers such a high load ... If the system usage increases I fear that 
it will be swamped and I would like to resolve this.

Anyone with any ideas????

root at xxxxx:~# uname -a
Linux xxxxx 2.6.10 #1 Mon Feb 21 11:29:51 SGT 2005 i686 GNU/Linux

root at xxxxx:~# dmesg | grep megaraid
megaraid: found 0x101e:0x1960:bus 0:slot 7:func 0
megaraid: [6.62:1.03] detected 1 logical drives.
megaraid: supports extended CDBs.
megaraid: channel[0] is raid.
megaraid: channel[1] is raid.
megaraid: channel[2] is raid.
megaraid: channel[3] is raid.

root at xxxxx:~# cat /proc/megaraid/hba0/config
v2.00.3 (Release Date: Wed Feb 19 08:51:30 EST 2003)
CERC ATA100/4ch
Controller Type: 438/466/467/471/493/518/520/531/532
Controller Supports 40 Logical Drives
Controller capable of 64-bit memory addressing
Controller is not using 64-bit memory addressing
Base = f8802000, Irq = 10, Logical Drives = 1, Channels = 4
Version =6.62:1.03, DRAM = 16Mb
Controller Queue Depth = 254, Driver Queue Depth = 126
support_ext_cdb    = 1
support_random_del = 1
boot_ldrv_enabled  = 1
boot_ldrv          = 0
boot_pdrv_enabled  = 0
boot_pdrv_ch       = 0
boot_pdrv_tgt      = 0
quiescent          = 0
has_cluster        = 0

Module Parameters:
max_cmd_per_lun    = 63
max_sectors_per_io = 128

root at xxxxx:~# cat /proc/megaraid/hba0/raiddrives-0-9
Logical drive: 0:, state: optimal
Span depth:  1, RAID level:  5, Stripe size: 64, Row size:  4
Read Policy: Adaptive, Write Policy: Write thru, Cache Policy: Direct IO

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