LinuxQuestions.org
Welcome to the most active Linux Forum on the web.
Go Back   LinuxQuestions.org > Forums > Linux Forums > Linux - Server
User Name
Password
Linux - Server This forum is for the discussion of Linux Software used in a server related context.

Notices



Reply
 
Search this Thread
Old 09-10-2010, 09:47 AM   #1
lukeMajorCS
LQ Newbie
 
Registered: Sep 2010
Posts: 1

Rep: Reputation: 0
Could a single spinning disk really be getting 1700 IOPS


I've got an IBM x3550 M2s (2 x 4w nehalem 2.93Ghz, 32GB ddr3 1333GHz, with 1 x 300GB 10K disk SATA). I'm running an application which is a heavy database (DB2) workload with a lot of writes. I've collected iostat data on the run with 10 second intervals. The average (r/s + w/s) iops is 744 iops and there is a max of 1733 iops. For the 1733 point, 1731 of the iops are writes, the wsec/s is 15934, avgqu_sz is 3.9, await is 2.25, svctm is .56. Everything I've read says a single drive can only handle between 120-150 iops. So, how could the iops average be over 700 and be able to reach over 1700? Is this the affects of caching, could the mix of sequential and random IO explain this, is the iops only an indication of the requests going to the drive--while the 120-150 range is what a drive is really handling so everything else is being queued?
 
Old 09-11-2010, 02:54 PM   #2
business_kid
Guru
 
Registered: Jan 2006
Location: Ireland
Distribution: Slackware & Android
Posts: 6,616

Rep: Reputation: 585Reputation: 585Reputation: 585Reputation: 585Reputation: 585Reputation: 585
I don't think you're going to get an accurate picture that way.

There's caching going on all over the place. The kernel caches, and writes to the disk cache of the drive. Probably the controller caches as well. It has to select the drive each time, as sata allows more than 1 drive per connection. Perhaps talk about partitions and directories. Go figure.

What does hdparm -tT say?
 
  


Reply

Tags
disk, performance


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
IOPS on multiple server single mount point system hyperactive22 Linux - Server 1 05-29-2010 03:29 AM
Hard disk constantly spinning almcneill Suse/Novell 6 04-30-2008 10:59 AM
spinning down hard disk sulekha Ubuntu 3 10-26-2007 10:17 AM
Hard Disk not spinning down (is that bad?) l00zer Linux - Laptop and Netbook 2 11-06-2004 12:15 AM
why is my disk spinning up? mattl Linux - General 2 06-07-2004 04:58 PM


All times are GMT -5. The time now is 04:45 PM.

Main Menu
Advertisement
My LQ
Write for LQ
LinuxQuestions.org is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
Syndicate
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
identi.ca: @linuxquestions
Facebook: linuxquestions Google+: linuxquestions
Open Source Consulting | Domain Registration