RE: I/O Performance/bottlenecks on EMC Symmetrix

[Loughmiller, Greg]

Title: RE: I/O Performance/bottlenecks on EMC Symmetrix

We saw this at a previous location and we found that we had logical volumes on the same disk.. Used for different applications, and even different systems!!  For example-someone placed TEMP for DB1 and TEMP for DB2 on the same disk unknowingly....  This created just a small contention problem...

 

This is a common problem when large sym cabinets are set up with "logical volumes split to different systems".

Each LV may be defined such that you wont know that they are on the same disk.  If you are using BCV's, and clustering-it get's even more detailed and confusing...

 

Have the EMC rep come in, take a look at the "bin" file of your sym cabinet(s).. And see where the logical volumes are living..  Draw a map of the bin file with a graphical representation of each LV, and where they live...

 

Greg

-----Original Message-----
From: Hallas John [mailto:[EMAIL PROTECTED]]
Sent: Thursday, September 13, 2001 10:01 AM
To: Multiple recipients of list ORACLE-L
Subject: RE: I/O Performance/bottlenecks on EMC Symmetrix

At one site I worked using Oracle Financials we were having serious performance problems at what seemed to us random intervals. Spent months looking at the database after the Unix boys had said that there was no way we could have I/O problems with the throughput capabililities of EMC and the Symetrix set up we had.

Eventually turned out that 3 systems were sharing the same disks and the disks had not been striped. Therefore other system were causing us performance problems.

If you have an EMC support contract which I think you must have you, the SA's get all the free GUI tools that allow them to look at channels and logical/physical layout. Ask them about.

John

-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
Sent: 13 September 01 12:55
To: Multiple recipients of list ORACLE-L
Subject: I/O Performance/bottlenecks on EMC Symmetrix

!! Please do not post Off Topic to this List !!

Hi All,

Does anybody here on the list have experience with EMC/symmetrix storage
units.?

We have our databases on this machine and I have a feeling the the I/O
performance is not very good. I can not proof it since I do not have any
experience/data/access to that machine. We do however have a very
cooperative UNIX group but they also lack experience with performance on
this machine.

Who can give me pointers about I/O throughput that can be reached,
configuration pittfalls etc..

Example:
RS6000 8CPU's and 4Gb memory with storage on EMC/symmetrix. Job takes about
2 hours to complete.

F50 1 CPU 1Gb memory (TEST machine) local disks. same job takes 0.5 hours
to complete.

Jack

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