Unsolved
This post is more than 5 years old
7 Posts
0
1106
April 9th, 2009 02:00
Powerpath : performance and check I/O loadbalance
Hi gurus
I have a question on Powerpath. I know it does load balacing, as well as path failover. In our environment we have 4 paths specifically to a LUN and we are told that if one path goes down, the performance of the DB or whatever it is using that LUN, wont be affected because the other 3 paths will take care of the IO for that LUN. The only thing that would be decreasing is redundant paths to that LUN.
Is this correct? How can we be sure that the performance of a database/application running on that LUN (which has one dead path) is the same as before? Is there a way to check/monitor how the I/O is loadbalance between the paths, with Powerpath?
Appreciate your replies! If this has already been explained in other threads, kindly let me know so I can have a look at those too.
-Ayla
I have a question on Powerpath. I know it does load balacing, as well as path failover. In our environment we have 4 paths specifically to a LUN and we are told that if one path goes down, the performance of the DB or whatever it is using that LUN, wont be affected because the other 3 paths will take care of the IO for that LUN. The only thing that would be decreasing is redundant paths to that LUN.
Is this correct? How can we be sure that the performance of a database/application running on that LUN (which has one dead path) is the same as before? Is there a way to check/monitor how the I/O is loadbalance between the paths, with Powerpath?
Appreciate your replies! If this has already been explained in other threads, kindly let me know so I can have a look at those too.
-Ayla
No Events found!
dynamox
9 Legend
•
20.4K Posts
0
April 9th, 2009 04:00
Conor
341 Posts
0
April 9th, 2009 06:00
HBA's are rarely operating at 100% throughput constantly unless it is an extremely IO intensive environment.
To see what kind of throughput your HBA;s are operating at use the usual performance tools like iostat and sar -d
SKT2
2 Intern
•
1.3K Posts
0
April 9th, 2009 10:00
Allen Ward
4 Operator
•
2.1K Posts
0
April 13th, 2009 09:00
In order to determine the threshold you would have to calculate the maximum sustained rate you want a single port to run at and them balance the load to ensure that you never go over that even with one path down.
Now, having said that it is still highly dependant on the answer to Dynamox's question: What is the array?
If you are connected to a Symm (with active/active pathing) then this is true. If you are connected to a CLARiiON (with active/passive pathing) then it is a whole different ballgame.
On a CLARiiON, only two of your four paths will be active. A failure on one path will drive all the I/O down another path. You would have to have a failure on two paths to the same SP in order to fail over to the other two paths (on the other SP). In this case you should never drive your HBAs beyond half the maximum capacity you ever want to push through.
Complicated enough?
Conor
341 Posts
0
April 13th, 2009 12:00
Cheers
Conor
Allen Ward
4 Operator
•
2.1K Posts
0
April 14th, 2009 10:00