Thank You Shane.
Currently we have a default IORM objective set as "BASIC". In our case it's
one database in that exadata half rack box and it has a mixed workload
running in it. We suffered mainly when , a large smart scan was running ,
scanning thousands of partitions and thus doing lot of large reads, and at
same time we have OLTP workload came to picture and they were started
slowing down(mostly because they were getting served from hard disk
rather flash as flash was occupied by the large reads smart scan query).
And, I read in a few blogs and also our DBA's suggesting AUTO will only
work or manage the IO in case multiple databases are hosted on the
exadata machine.
So my doubt was, will AUTO objective help us here giving priorities to low
latency queries in the intra database workload? In other words, How "AUTO"
objective decides which workload it will give priorities to?
Or
Should we dynamically switch between two different objective "Low latency"
VS "BASIC" each day. And is it possible to do online through automated
script ,without impacting anything else?
On Fri, Nov 20, 2020 at 1:53 AM Shane Borden <sborden76@xxxxxxxxx> wrote:
I use AUTO all the time and it is my go to IORM plan if I want to manage
I/O and allow the system to try to do it first. If that doesn’t produce
the desired result, then I will start to make my own plans, but it becomes
very difficult to get it right.
---
Thanks,
Shane Borden
sborden76@xxxxxxxxx
407-963-4883
On Nov 19, 2020, at 2:58 PM, Lok P <loknath.73@xxxxxxxxx> wrote:
It looks to me as if DB resource managers are purely made for CPU
management, and with that respect , I doubt it will be effective in
managing the storage cell I/O, and that is why IORM(IO resource manager)
has come into picture. But sadly it's not documented properly. And in most
of the cases it says it manages inter database workload only. But we are
facing issues with intra database workload management. I got below blog
stating how AUTO objectives for IORM fixed the issue of IO management. So
has anybody used AUTO objective for managing INTRA databases workload?
https://weidongzhou.wordpress.com/2013/08/23/awr-is-not-enough-to-track-down-io-problem-on-exadata/
On Thu, Nov 19, 2020 at 2:29 AM Lok P <loknath.73@xxxxxxxxx> wrote:
We have one database with version 11.2.0.4 Exadata-X5 machine. We have
IORM objective kept as BASIC(which is default) and it's only one database
in that half RACK(~7 cell server) exadata cluster. We encountered
performance issue twice , where a ETL query doing FULL table/partition scan
repetitively for longer duration, causing the flash cache to be flooded
with large reads and the other low latency work load or small reads/index
reads getting suffered because of that, and so we had to kill the ETL query
to let the low latency workload perform in its normal speed.
I saw in a few blogs stating the IORM should be kept as AUTO and is
recommended. Wanted to understand from experts, if AUTO IORM setup is going
to help in such a situation, where we have only one database residing in
the exadata machine having multiple types of workloads(both OLTP and BATCH
types at same time) running in the same database? I am not seeing a clear
difference , how different is IORM objective AUTO from the BASIC incase of
single database IORM management?
