# # amird driver, BDFLUSH and NAUTOUP, and more
APLawrence.com -  Resources for Unix and Linux Systems, Bloggers and the self-employed

amird driver, BDFLUSH and NAUTOUP, and more

I've removed advertising from most of this site and will eventually clean up the few pages where it remains.

While not terribly expensive to maintain, this does cost me something. If I don't get enough donations to cover that expense, I will be shutting the site down in early 2020.

If you found something useful today, please consider a small donation.



Some material is very old and may be incorrect today

© August 2004 Tony Lawrence

I recently installed a new SCO 5.0.7 server to replace an older SCO 5.0.5 system. We put in new hardware, with an LSI Ultra-320 raid controller. Two drives were configured for hardware mirroring. That hardware uses the AMIRD driver, and the installation was quick and simple.

I checked disk performance against the old server with various permutations of "timex dd if=/dev/root of=/tmp/this bs=1024 count=8192", using different block sizes and counts, and also adding some seeks. I did these on both machines, with some tests including intermediate "ls -lR /u" to clear the buffer cache and some not, and in general I could say that the new machine was 6 times faster for disk access and a little more so for buffer cache accesses.

Imagine my surprise when the customer reported that it seemed slower to them.

Well, I knew that /etc/idrc.d/amird might be at fault, so I added an "exit 0" at the top of that script and killed the /etc/amirdmon process that it had started. That helped a little, but they still complained of sluggishness. I could see that in "sar -d", too:


12:00:00 Sdsk-0    26.95      1.00      0.67      5.30      0.00    400.15

12:20:00 Sdsk-0     9.58      1.00      0.82      2.92      0.00    116.44

12:40:01 Sdsk-0     9.65      1.00      0.72      1.92      0.00    134.11

13:00:03 Sdsk-0     5.81      1.00      1.17      5.15      0.00     49.57

13:20:00 Sdsk-0     6.28      1.00      0.42      1.07      0.00    148.58

13:40:00 Sdsk-0     2.10      1.00      0.12      0.27      0.00    179.93

14:00:00 Sdsk-0    24.20      1.01      1.72      6.52      1.44    141.05

14:20:00 Sdsk-0    29.65      1.01      0.57      1.42      5.85    517.83

14:40:00 Sdsk-0    29.33      1.00      2.12      6.13      0.00    138.62

15:00:00 Sdsk-0    15.44      1.00      1.16      2.98      0.00    133.49

15:20:00 Sdsk-0   100.00      1.01      5.61     19.16      2.28    322.97


Average  Sdsk-0    48.04      1.02      1.43      6.29      6.55    336.06
 

I couldn't get the command line scodb to work for me over my ssh connection, so I had to use /etc/conf/cf.d/configure to modify BDFLUSH and NAUTOUP to "1". . Relink, reboot, and sar was much happier:

15:38:41  device   %busy     avque     r+w/s    blks/s    avwait    avserv (-d)
15:38:56 Sdsk-0     0.20      1.00      1.93      4.40      0.00      1.03

15:39:11 Sdsk-0     0.07      1.00      2.13      7.73      0.00      0.31

15:39:26 Sdsk-0     1.53      1.00      3.40     10.93      0.00      4.51

15:39:41 Sdsk-0     1.33      1.00      3.40     11.59      0.00      3.92

15:39:56 Sdsk-0     1.00      1.00      1.33      2.93      0.00      7.50

15:40:11 Sdsk-0     1.60      1.00      4.27     13.87      0.00      3.75

15:40:26 Sdsk-0     0.07      1.00      0.27      0.67      0.00      2.50

15:40:41 Sdsk-0     1.60      1.00      4.13     10.80      0.00      3.87

15:40:56 Sdsk-0     0.13      1.00      1.27      4.40      0.00      1.05

15:41:11 Sdsk-0     0.40      1.00      1.67      6.93      0.00      2.40
 

The users were now able to agree that the system was faster.


If you found something useful today, please consider a small donation.



Got something to add? Send me email.





(OLDER)    <- More Stuff -> (NEWER)    (NEWEST)   

Printer Friendly Version

->
-> amird driver, BDFLUSH and NAUTOUP, and more


Inexpensive and informative Apple related e-books:

Are Your Bits Flipped?

iOS 10: A Take Control Crash Course

Digital Sharing Crash Course

El Capitan: A Take Control Crash Course

Take Control of Numbers





More Articles by © Tony Lawrence




I'm wondering if part of the problem is the LSI controller? I've had mixed results with their RAID adapters, and in fact, seem to recall that they were inferior in terms of short, random access reads to the Mylex units I was using at the time. But, of course, it could be something deep inside the 5.0.7 kernel itself. Who knows?

--BigDumbDinosaur



Printer Friendly Version

Have you tried Searching this site?

This is a Unix/Linux resource website. It contains technical articles about Unix, Linux and general computing related subjects, opinion, news, help files, how-to's, tutorials and more.

Contact us


Printer Friendly Version





Computers are like Old Testament gods; lots of rules and no mercy. (Joseph Campbell)




Linux posts

Troubleshooting posts


This post tagged:

Blog

Disks/Filesystems

Hardware

Kernel

Performance



Unix/Linux Consultants

Skills Tests

Unix/Linux Book Reviews

My Unix/Linux Troubleshooting Book

This site runs on Linode