Solved

Disk queue length performance object

Posted on 2013-01-31
5
1,291 Views
Last Modified: 2016-11-23
I have Dell PowerEdge server with 20 x 600GB 10RPM SAS drives in a single RAID6 array.

What is the value of Disk Queue Length performance object that would indicate a bottleneck?

I'm trying to figure if out how much this server can handle

Thank you
0
Comment
Question by:piotrmikula108
  • 3
  • 2
5 Comments
 
LVL 16

Accepted Solution

by:
choward16980 earned 500 total points
ID: 38841776
Which poweredge, which PERC controller?

My rule of thumb is to have users create time stamps for when they experience I/O pauses by putting an icon that appends a times stamp and username.  I then go back to my performance monitor and review the disk queue length logs and see if the I/O pauses my users are reporting correlate to the log data.


http://www.sql-server-performance.com/forum/threads/average-disk-queue-length.8384/
quote:
"If Avg. Disk Queue Length counter exceeds 2 for continuous periods (over 10 minutes or so during your 24 hour monitoring period) for each disk drive in an array, then you may have an I/O bottleneck for that array"
0
 
LVL 1

Author Comment

by:piotrmikula108
ID: 38841832
PE720XD with Perc H710 mini controller

So since I have 20 drives I could have the queue up to say 35 to be under 2 per spindle? I know I'm simplifying things...
0
 
LVL 16

Expert Comment

by:choward16980
ID: 38842566
Do you know what kind of array the 20 drives are arranged in?  Parity must be considerd as a standard RAID-5 is typically 20-25% parity overhead.
0
 
LVL 1

Author Comment

by:piotrmikula108
ID: 38842587
Raid6
0
 
LVL 16

Assisted Solution

by:choward16980
choward16980 earned 500 total points
ID: 38842695
This guy says >4 for user impact:

http://www.experts-exchange.com/Software/Server_Software/Q_22868359.html

So RAID6 (20 drives - 2 ) * 600GB = 18 drives * 4 = 72.

So by that rule of thumb, >72 would = user impact.

Single controller throughput (6/Gb/s)  pci-e 2.0 (4.0/Gb/s)  so 66% of 72 = 47.52

I would assume anything > 48 would effect the user.
0

Featured Post

PRTG Network Monitor: Intuitive Network Monitoring

Network Monitoring is essential to ensure that computer systems and network devices are running. Use PRTG to monitor LANs, servers, websites, applications and devices, bandwidth, virtual environments, remote systems, IoT, and many more. PRTG is easy to set up & use.

Question has a verified solution.

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

Suggested Solutions

Title # Comments Views Activity
NTFS Permissions 6 48
DNS issue with resolving request 14 87
Set up secondary Domain Controller 4 71
Group Managed Service Account Permissions 3 20
You might have come across a situation when you have Exchange 2013 server in two different sites (Production and DR). After adding the Database copy in ECP console it displays Database copy status unknown for the DR exchange server. Issue is strange…
It’s been over a month into 2017, and there is already a sophisticated Gmail phishing email making it rounds. New techniques and tactics, have given hackers a way to authentically impersonate your contacts.How it Works The attack works by targeti…
This tutorial will walk an individual through locating and launching the BEUtility application to properly change the service account username and\or password in situation where it may be necessary or where the password has been inadvertently change…
Windows 8 came with a dramatically different user interface known as Metro. Notably missing from that interface was a Start button and Start Menu. Microsoft responded to negative user feedback of the Metro interface, bringing back the Start button a…

810 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