[Webinar] Streamline your web hosting managementRegister Today

x
  • Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 1349
  • Last Modified:

Disk queue length performance object

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
piotrmikula108
Asked:
piotrmikula108
  • 3
  • 2
2 Solutions
 
Chris HInfrastructure ManagerCommented:
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
 
piotrmikula108Author Commented:
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
 
Chris HInfrastructure ManagerCommented:
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
 
piotrmikula108Author Commented:
Raid6
0
 
Chris HInfrastructure ManagerCommented:
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

Problems using Powershell and Active Directory?

Managing Active Directory does not always have to be complicated.  If you are spending more time trying instead of doing, then it's time to look at something else. For nearly 20 years, AD admins around the world have used one tool for day-to-day AD management: Hyena. Discover why

  • 3
  • 2
Tackle projects and never again get stuck behind a technical roadblock.
Join Now