IBM AIX Internal HDD vs SAN HDD and Oracle


 
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Operating Systems AIX IBM AIX Internal HDD vs SAN HDD and Oracle
# 1  
Old 01-12-2014
IBM AIX Internal HDD vs SAN HDD and Oracle

Hi Folks,

I am facing an issue with the performance.

P4 with 1 processor and 16 GB RAM and SAN HDD = Oracle report takes 25 minutes

P5 with 2 processors and 16 GB RAM internall HDD with LPAR = Oracle Report takes 1 hour 15 minutes ( please note I have assigned all the max processors and memory to this LPAR and this is the only LPAR active )

* How can I measure and troubleshoot to find out what is causing the delay ?

Any help and insight would be appreciated
# 2  
Old 01-13-2014
We have seen differences in performance of a similar scale and nature.

Internal/local disk is managed by your server and it is responsible for all the real IO, writing the bits to the disk controllers and getting the acknowledgement when the update is made to the brown-spinning part.

With SAN storage, the request by your OS to write data is accepted and confirmed by the SAN before the data is really written to disk. It's written to the SAN cache, but as far as your OS is concerned, then transaction is complete and processing can continue.


A SAN disk array will have a large cache dedicated to holding write requests and flushing them to real disk in large IO writes. This is why all SAN disk arrays will have batteries to keep the cache alive in the event of a power failure. This is in addition to any UPS you may have in place. A SAN shutdown can also be done in two ways roughly described as immediate and controlled. In the controlled shutdown, the cache is flushed and the SAN disk is consistent. An Immediate shutdown does not flush the cache and is quicker. It has no difference for the actual data stored unless the battery fails or is replaced.


As to a way to measure it, I suppose you are into creating a large complex file and copying it about a few times. By complex, I mean something that compression software will not easily deal with. My way to do this (mainly for testing FTP speed) is to tar up some large files and compress them, then append them a few times to get the size big enough.

If your hardware can support it, then it can be beneficial to have everything as SAN storage, including the OS and paging space. The limitation then becomes the connection speed to the SAN.

If you replicate your SAN to another site, then this takes care of updates to the boot disks / rootvg / vg00 (whatever you want to call it) that may affect the DR position. Of course, the IP address will be replicated so you have to handle that along with a process to use perhaps different hardware at the remote site.

It is, however no substitute for backups as errors / corruption will also be replicated honestly.



I hope that this helps.

Robin
Liverpool/Blackburn
UK
# 3  
Old 01-13-2014
This type of question really need one to drill down to the core of the system and perform an autopsy.

Is both OS and DB version same and size of DB equal on those systems?

Are you running same queries (doing the same activity as on the other system)?

If no, then what is the version of OS on both? Have you tuned the system on latter as per the standard? (like Memory tuning).

How ample is the network bandwidth, what is the type of storage.

What version of oracle DB you are using on both?

Are there any patches for oracle and APAR for AIX to apply and have you looked out for those?

In short these types of questions cannot be answered easily.
# 4  
Old 01-14-2014
Just to add to ibmtechs list (which is very good already):

What are the respective sizes of the SGA?

What is the output of "vmstat -v"?

I hope this helps.

bakunin
# 5  
Old 01-15-2014
Okay,

#1 Rbattle

I am using P550 VIOS so it cannot have a dedicated SAN HBA card,

Have to first assign the HDISK from SAN to I/O VIOS server and then from VIOS to LPAR

#2 IBMTECH and Bakunin

Yes, both database size are exactly same, infact it is a clone of the production environment, the min max paging space and other parameters are also same.... everything is same. DATA, DATABASE, Parameters, OS,
only difference
ORADB = Production Environment runs on P4 and Oracle is on SAN = report take 25 minutes
CloneDB = Clone Environment runs on P5 and Oracle is on internal Disks = report takes 1 hour and 15 minutes

AIX P4 = PRODUCTION
Code:
root@oradb:/>pagesize -a
4096

root@oradb:/>vmstat -v
              4194304 memory pages
              4000247 lruable pages
                 9961 free pages
                    1 memory pools
               218074 pinned pages
                 80,1 maxpin percentage
                 20,0 minperm percentage
                 80,0 maxperm percentage
                 80,3 numperm percentage
              3214895 file pages
                  0,0 compressed percentage
                    0 compressed pages
                  0,0 numclient percentage
                 80,0 maxclient percentage
                    0 client pages
                    0 remote pageouts scheduled
                   53 pending disk I/Os blocked with no pbuf
                    0 paging space I/Os blocked with no psbuf
                80406 filesystem I/Os blocked with no fsbuf
                    0 client filesystem I/Os blocked with no fsbuf
                    0 external pager filesystem I/Os blocked with no fsbuf

AIX P5 ON LPAR = CLONE
Code:
pagesize -a
4096
root@clodb:/>vmstat -v
              2097152 memory pages
              2017797 lruable pages
              1713122 free pages
                    2 memory pools
               121734 pinned pages
                 80.0 maxpin percentage
                  5.0 minperm percentage
                 90.0 maxperm percentage
                  0.7 numperm percentage
                14208 file pages
                  0.0 compressed percentage
                    0 compressed pages
                  1.2 numclient percentage
                 90.0 maxclient percentage
                24760 client pages
                    0 remote pageouts scheduled
                    0 pending disk I/Os blocked with no pbuf
                    0 paging space I/Os blocked with no psbuf
                 2740 filesystem I/Os blocked with no fsbuf
                    0 client filesystem I/Os blocked with no fsbuf
                    0 external pager filesystem I/Os blocked with no fsbuf


ORACLE ON CLONE AIX ENV P5 LPAR

Code:
oraprod@clodb:/oratech/proddb/9.2.0/>./startup.sh

You are running addbctl.sh version 115.8


Starting the database PROD ...


SQL*Plus: Release 9.2.0.3.0 - Production on Wed Jan 15 14:16:00 2014

Copyright (c) 1982, 2002, Oracle Corporation.  All rights reserved.

Connected to an idle instance.
ORACLE instance started.

Total System Global Area  615482512 bytes
Fixed Size                   742544 bytes
Variable Size             436207616 bytes
Database Buffers          167772160 bytes
Redo Buffers               10760192 bytes
Database mounted.
Database opened.
Disconnected from Oracle9i Enterprise Edition Release 9.2.0.3.0 - 64bit Production
With the Partitioning, OLAP and Oracle Data Mining options
JServer Release 9.2.0.3.0 - Production

addbctl.sh: exiting with status 0


You are running addlnctl.sh version 115.6

Logfile: /oratech/proddb/9.2.0/appsutil/log/PROD_clodb/addlnctl.txt

Starting listener process PROD ...


addlnctl.sh: exiting with status 0
oraprod@clodb:/oratech/proddb/9.2.0/>
oraprod@clodb:/oratech/proddb/9.2.0/>sqlplus

SQL*Plus: Release 9.2.0.3.0 - Production on Wed Jan 15 14:19:04 2014

Copyright (c) 1982, 2002, Oracle Corporation.  All rights reserved.

Enter user-name: sys
Enter password:

Connected to:
Oracle9i Enterprise Edition Release 9.2.0.3.0 - 64bit Production
With the Partitioning, OLAP and Oracle Data Mining options
JServer Release 9.2.0.3.0 - Production

SQL> connect as sysdba
Enter user-name: sys
Enter password:
Connected.


SQL> show parameters area_size

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
bitmap_merge_area_size               integer     1048576
create_bitmap_area_size              integer     8388608
hash_area_size                       integer     131072
sort_area_size                       integer     65536
workarea_size_policy                 string      AUTO

SQL> set pages 999; column pga_size format 999,999,999;

SQL> select
    1048576+a.value+b.value   pga_size
from
   v$parameter a,
   v$parameter b
where
   a.name = 'sort_area_size'
and
   b.name = 'hash_area_size'
;

 PGA_SIZE
------------
   1,245,184

# 6  
Old 01-15-2014
Quote:
Originally Posted by filosophizer
Yes, both database size are exactly same, infact it is a clone of the production environment, the min max paging space and other parameters are also same.... everything is same. DATA, DATABASE, Parameters, OS,
only difference
ORADB = Production Environment runs on P4 and Oracle is on SAN = report take 25 minutes
CloneDB = Clone Environment runs on P5 and Oracle is on internal Disks = report takes 1 hour and 15 minutes
This way it sounds more logical, because SAN disks are (in most cases) much faster than physical disks. They have usually a lot more IOPS and more throughput bandwidth, because a lot of different reasons: stripesets, caching controllers, buses with higher bandwidth, ....

Your systems seem not to have the same amount of memory at all:

Code:
root@oradb:/>vmstat -v
              4194304 memory pages
              [...]
root@clodb:/>vmstat -v
              2097152 memory pages
              [...]

Further this looks dubious:
Code:
root@oradb:/>vmstat -v
                [...]
                80406 filesystem I/Os blocked with no fsbuf
                [...]

whereas:
Code:
root@clodb:/>vmstat -v
                 [...]
                 2740 filesystem I/Os blocked with no fsbuf
                 [...]

Not the value in itself is problematic, but the huge difference. Monitor the value closely over time, if it increases heavily you have found a potential bottleneck. If it stays at this level it is perhaps an artefact of some temporary memory shortness.

Finally, the tuning parameters seem to be different (compare "maxperm" and "minperm" in the different outputs, probably others are different too). You should run "vmo -a" (and the other tuning utilities, "schedo", "ioo", "no") on both machines to investigate other differences. What good values for maxperm and minperm would be is hard to suggest because it depends heavily on the (detailed) OS version which we do not know.

Another supposition (which would have to be proven by facts) of mine is that the faster processor is not needed in the special kind of report you run and therefore contributes nothing to some faster execution, whereas the disks contribute heavily.

I hope this helps.

bakunin
# 7  
Old 01-15-2014
And to add more to bakunin's finding, have you enable AIO? ( I assume you are using AIX5.3, given the specification of hardware). Did you cross verify that CIO option for DB file systems is enabled on Prod system (if AIX5.3 or less).
Can you provide us the VMM parameters that are currently configured in both systems?
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