Solved

Disk I/O capacity

Posted on 2013-11-20
7
699 Views
Last Modified: 2013-11-20
We are experiencing some poor performance on our web application during a small stress test.  We would like to determine the IOPS consumption of the application so we can evaluate the storage system.   It is a Red Hat Linux/Oracle server running in VMware ESXi 4.1.  What tools can I use to capture the necessary data needed to analyze ?
0
Comment
Question by:NytroZ
  • 2
  • 2
  • 2
  • +1
7 Comments
 
LVL 40

Accepted Solution

by:
coolsport00 earned 250 total points
ID: 39664213
If you are thinking it is simply disk latency the VM resides on based on disk in & of itself (i.e. a misconfigured datastore for RAID, etc.), you can SSH into the Host the VM resides on, type "esxtop" (no quotes), then press 'v' & view the DAVG statistic for the VM. If it is above 10-12ms, your underlying storage is having issues. You need either more spindles in the RAID, a different RAID, or different disk types (i.e. SAS or SSD rather than potentially SATA).

~coolsport00
0
 
LVL 120
ID: 39664228
0
 

Author Comment

by:NytroZ
ID: 39664236
The current setup is 4 10K SAS disks in a RAID 10.  I was told this can do about 300 IOPS/sec.  Looking at the performance tab on the vSphere client it shows the IOPS around 1000 during a load.  Is this accurate?  If the disks are only capable of 300 IOPS how is it recording 1000 IOPS?  I will try the extop command.
0
Windows Server 2016: All you need to know

Learn about Hyper-V features that increase functionality and usability of Microsoft Windows Server 2016. Also, throughout this eBook, you’ll find some basic PowerShell examples that will help you leverage the scripts in your environments!

 
LVL 120
ID: 39664268
Doing the calculations, approx 400 IOPs.
0
 

Author Comment

by:NytroZ
ID: 39664304
The esxtop command showed me the reads/writes per second at it verified what the performance chart showed me.  The IOPS are around 1000 and disk latency is 4ms.  this runs for a bit but eventually the database comes back with TNS listener timeout error.  Would it be safe to say that the disks are being overloaded even though latency is still low?
0
 
LVL 30

Assisted Solution

by:Duncan Meyers
Duncan Meyers earned 250 total points
ID: 39664314
When you're preparing sizing, each 10K drive can handle 140 IOPS average. They'll peak to about 2.5 x that, so 350 IOPS per drive absolute maximum. Beyond that, response time will go through the roof
Your RAID 1/0 set should be able to produce 1400 read IOPS peak assuming your RAID array is smart enough to distribute reads across all 4 drives. For writes, it'll handle a maximum of 700 host write operations. You haven't described what the stress test is and what the I/O distribution is, but I'd say that at 1000 IOPS, you're at the limits of what 4 drives can provide so you need to add more drives. Depending on what your shared storage is, you could add more drives or add SSDs to improve performance.

Incidentally, beware of chasing benchmark numbers. What's important is the user experience, not what the load generating or benchmarking software says. If you have 10 concurrent users hitting your web app, then I'd imagine performance of your existing configuration is fine. If, on the other hand, you're getting 10,000 concurrent users, well, you're in the poo and you need more disk
0
 
LVL 30

Expert Comment

by:Duncan Meyers
ID: 39664608
Thanks! Glad I could help.
0

Featured Post

NEW Veeam Agent for Microsoft Windows

Backup and recover physical and cloud-based servers and workstations, as well as endpoint devices that belong to remote users. Avoid downtime and data loss quickly and easily for Windows-based physical or public cloud-based workloads!

Question has a verified solution.

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

This article aims to explain the working of CircularLogArchiver. This tool was designed to solve the buildup of log file in cases where systems do not support circular logging or where circular logging is not enabled
When we purchase storage, we typically are advertised storage of 500GB, 1TB, 2TB and so on. However, when you actually install it into your computer, your 500GB HDD will actually show up as 465GB. Why? It has to do with the way people and computers…
Teach the user how to edit .vmx files to add advanced configuration options Open vSphere Web Client: Edit Settings for a VM: Choose VM Options -> Advanced: Add Configuration Parameters:
This tutorial will walk an individual through the process of installing the necessary services and then configuring a Windows Server 2012 system as an iSCSI target. To install the necessary roles, go to Server Manager, and select Add Roles and Featu…

749 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