Into.the.Void.

Lately I had to deal with some HP raid controllers and I’ve gathered some notes on them. I’ll post them here so I won’t forget about them.

First of all, don’t even think on using them without a battery pack. Seriously DON’T. The performance degradation is humongous. Without a battery pack the controllers were giving me 1/20th of the results with a battery pack. If you want to quickly test them, try iozone using the following options: iozone -t4 -I

Installing hpacucli is a also a must if you want to monitor or configure the controllers from within your OS. Be sure to add the repositories from HWraid to your system and then issue: aptitude install hpacucli (you are using Debian, arent’ you?). That reminds me that I am using those repositories on so many systems I manage that I must send a donation to the people at hwraid to thank them.

Below are some commands using hpacucli that I used.
# Show everything about your raid controllers
# hpacucli controller all show config detail

Cache Board Present: True
Cache Status: OK
Accelerator Ratio: 25% Read / 75% Write
Drive Write Cache: Enabled
Total Cache Size: 512 MB
Battery Pack Count: 1
Battery Status: OK
SATA NCQ Supported: True

What you must take notice here is the Accelerator Ratio, Drive Write Cache and Battery Pack Count.
if you have a battery pack installed but your Drive Write Cache is still shown as “Disabled”, you can enable it using the command:
# hpacucli controller slot=X modify dwc=enable
You’ll know what to put instead of “slot=X” from the output of the previous command (show config detail).

To modify Accelerator Ratio (read/write):
# hpacucli controller slot=X modify cacheratio=25/75

To enable Array Acceleration for one of your logical drives use:
# hpacucli controller slot=X logicaldrive Y modify aa=enable

If you happen to face the following error while opening hpacucli, don’t worry. You don’t need to reboot your machine as I’ve seen in various blogs.

Error: Another instance of ACU is already running (possibly a service). Please
terminate the ACU application before running the ACU CLI. Press ENTER to
exit.

What you need to do is delete the shared IPC that hpacucli left when it got killed for some reason.
To see all your ipcs:

# ipcs
------ Shared Memory Segments --------
key        shmid      owner      perms      bytes      nattch     status      

------ Semaphore Arrays --------
key        semid      owner      perms      nsems     
0xffffffff 32768      root       0          1         

------ Message Queues --------
key        msqid      owner      perms      used-bytes   messages    

Then use ipcrm to remove the array with the semid you want:
# ipcrm -s 32768

and try to start hpacucli again.

References:
1. http://www.datadisk.co.uk/html_docs/redhat/hpacucli.htm
2. http://people.freebsd.org/~jcagle/hpacucli-readme

Filed by kargig at 12:15 under Linux
Tags: Accelerator ratio, cache ratio, debian, HP, hpacucli, Linux, P410, raid, raid controller, storage, sysadmin, Write Cache
6 Comments | 11,331 views