Still celebrating National IT Professionals Day with 3 months of free Premium Membership. Use Code ITDAY17

x
?
Solved

Raid 5 slow sequential write speed

Posted on 2006-06-14
11
Medium Priority
?
806 Views
Last Modified: 2010-03-16
I have an hp ProLiant server with 3 72.8 G ULTRA320 SCSI drives set up as a RAID 5 array.  When I run a PassMark performance test on the disk it gives me a 6.3 MBytes/Sec write speed.  A comperable machine gives a write speed of 56.4.  Does anyone have any tips to troubleshoot this problem?
0
Comment
Question by:mhalp200
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
11 Comments
 
LVL 69

Expert Comment

by:Callandor
ID: 16905537
Check the status of the array and make sure it is not in a degraded state.  You should also run diagnostics on each drive from the controller, to see if any are failing.  Try another cable as well, check if the SCSI ids are correctly jumpered for all devices, and make sure the termination is set properly (one on each end of the cable, either electronically or otherwise).
0
 

Author Comment

by:mhalp200
ID: 16905658
I ran an Array Diagnostic utility.  Id did not report any errors with the array.  It did however, report a sector size of 512 bytes, however, I had changed it, and chkdsk reports 4096 bytes.  Can this be related to the slowness.

I will check the cabling later.

Thanks
0
 
LVL 69

Expert Comment

by:Callandor
ID: 16905689
I've never tried a sector size other than 512; was there a reason you changed it?
0
VIDEO: THE CONCERTO CLOUD FOR HEALTHCARE

Modern healthcare requires a modern cloud. View this brief video to understand how the Concerto Cloud for Healthcare can help your organization.

 
LVL 44

Expert Comment

by:scrathcyboy
ID: 16908958
The benchmark will report a 10x slowness when it is (1) checking the raid for consistency, (2) writing the checksums, (3) refeshing the RAID redundancy, (4) have a driver that is not compatible with the OS, or (5) having sector read issues.  You should continue to test the array, and if the situation does not improve in a day or so, you should look at the drives in windows, make sure the RAID drivers are OK.  And if you continue to get problems, as long as there is no data lost or missing, run checkdisk.  If it still does not improve performance, look and upgrading the RAID BIOS from the HP website.  And if all that fails, you probably have a failing disk which is causing repeated reads.  Do you hear clicking from the drives?  If so, one is haing sector read errors, so it is time to replace it.  This RAID should do 65Mb ++.
0
 

Author Comment

by:mhalp200
ID: 16910495
I noticed that through the device manager in control panel, wrte caching is not enabled.  Could this be causing the slowness.

By the way there really is slowness - it noticed it before running the diagnostic utility.


0
 
LVL 69

Expert Comment

by:Callandor
ID: 16911736
Write caching is in the controller, and you should still see good results on reads.  I would say take apart the array and test the performance with each drive separately.
0
 
LVL 2

Expert Comment

by:Psyco_666
ID: 16919482
Have you looked at which way the cache is oriented? read vs write. Is this a 5i or a 5300 controller?
0
 
LVL 1

Accepted Solution

by:
macaulish earned 2000 total points
ID: 16922114
You cannot enable write caching through windows, you have to do it at the controller level.  If you have the 6i controller you won't be able to enable write caching unless you have a battery backed write cache enabler.  Raid 5 is not the best configuration for a server if you plan on writing the the disk a lot but if you purchase the HP 128MB BBWC and configure write caching you will see improved performance.

Hope this helps

Mike
0
 

Author Comment

by:mhalp200
ID: 16927294
Mike

Thanks,

I noticed before your post that windows does not allow me to enable write caching.  I'll purchase the HP 128MB BBWC.  If this allows me to enable toe wriote caching, and it greatly improves the sequential write speed, I will give you the points.
0
 

Author Comment

by:mhalp200
ID: 16955584
It worked!

I bought the HP 128MB BBWC and configured write caching.  I now get a benchmark speed of over 56.


Thanks



0
 

Expert Comment

by:tomsmorgan
ID: 27696861
Mhalp200,
Did you have to back up & restore to replace card, I have the same problem write 9mb/s read 111mb/s
with perc4/sc
SCSI is hard to image and restore
0

Featured Post

Meet the Family that is Made for Collaboration

The TeamConnect Family product group as part of the Sennheiser for Business Portfolio comprising high-quality, technically well-conceived meeting solutions for business communication – designed for any meeting room and any meeting situation.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Monitor input from a computer is usually nothing special.  In this instance it prevented anyone from using the computer.  This was a preconfiguration that didn't work.
This is about my first experience with programming Arduino.
In this brief tutorial Pawel from AdRem Software explains how you can quickly find out which services are running on your network, or what are the IP addresses of servers responsible for each service. Software used is freeware NetCrunch Tools (https…
Want to learn how to record your desktop screen without having to use an outside camera. Click on this video and learn how to use the cool google extension called "Screencastify"! Step 1: Open a new google tab Step 2: Go to the left hand upper corn…

715 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question