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Filip,

* More than 1ms or 2ms is bad for Record Level Access, but "maybe" it's ok for SQL. Depends on your programs
* Usually when you have more than 6ms you have poor performance
* You can go deeper and dig into Disk Wait Overview report, so you can try to identify this response time
* Are you using NPIV or vSCSI?
* What about Volume response time on V5010 Performance view?
* Can you go down CPU and then CPU Waits report?
* Can you check Paging?
* Have you moved your QZDASOINIT out of *BASE pool?
* Can you take a Database Snapshot and check long running queries with Visual Explain? (maybe you have already done this)
* Do you have Db2 Symmetric Multiprocessing running?
* Have you tried to get a FLiP Report? FLiP report can estimate improvement when using Flash System, but it's based on SSD Analyzer, so I think this can show you if disk matters.

Regards

Diego E. KESSELMAN


El 28/02/19 a las 12:19, Filip Drzewiecki via MIDRANGE-L escribió:
Well PDI have so many options that I'm totally lost. I have found something called Disk I/O Average response time and you can find screen using below IMGUR address:
https://imgur.com/a/WdY3W4H

Not sure if I read it correctly but when is transformed this to table I could see that in many cases average response time was 4-5 ms or even more. Whats more when I checked health indicator (guess some default values were used), this is what I saw:
https://imgur.com/a/1wSXBN3

I guess it answer at least one question about disk response time...


-----Original Message-----
From: MIDRANGE-L <midrange-l-bounces@xxxxxxxxxxxxxxxxxx> On Behalf Of Diego Kesselman
Sent: Thursday, February 28, 2019 3:03 PM
To: Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxxxxxxxx>
Subject: Re: Performance issues after moving more into SQL

You can use PDI to check for bottlenecks.
With more SQL I guess you need more memory and CPU.
If you are falling short in memory (lots of page faults above 200 on your
pool) your disk response time could be poor (>2ms)



El jue., 28 de feb. de 2019 07:55, Filip Drzewiecki via MIDRANGE-L < midrange-l@xxxxxxxxxxxxxxxxxx> escribió:

Hello,
I observe more and more performance issues with our application and
they started to show up after we've introduced a lot of SQL to our
system. We've did a lot of optimization but even after that we still
have some problems and I'm trying to understand what tools I can use
to see if hard drives are out bottleneck or maybe it is CPU.

System setup (from program/database perspective) is quite complicated.
We've moved from DDS to SQL tables(most tables) and MQT (materialized
query tables, biggest tables ) but programs were not changed and most
of them still use native I/O (but we have SQL behind because of RPG
Open Access and MQT/Indexes). I understand that we may have some
overhead because of this(on CPU) but for example MQT Updates/Insert
are quite slow but we use the for Read operation because chain
operation with sql behind was very slow without MQT. Of course we use SQL triggers in this setup.

We do not have EasyTier license and from what I've read it could tell
us if we could benefit from SSD. I've also found something about SSD
Analyzer (
http://www-01.ibm.com/support/docview.wss?uid=tss1prs3780) but only
for
7.1 and it look like it does not work on 7.3 (I could not see it as
collection in iNavigator

We have machine type 8286-41A (power8) with 3 LPARS which has few HDD
drives (raid 5) and StorWize 5010 with few HDD Drives. Unfortunately
we do not have VIOS and LPAR 1 (master) expose HDD to DEV LPAR and PROD LPAR.
This of course should and will be changed but to be honest I have no
idea how much performance we may get if we start use VIOS.

Now I'm totally lost which tools/commands could tell me if response
time from our HDD is weak point and this is why we have slow
read/write times and our CPU does nothing because it waits for HDD(and
we should buy few SSD for hot files). We have Performance Tool so I
can use collections services/performance monitor and then print one of
available reports but there are so many of them. I guess disk report can be used.

Do You have any advices what should I check here?


Filip
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El jue., 28 de feb. de 2019 07:55, Filip Drzewiecki via MIDRANGE-L < midrange-l@xxxxxxxxxxxxxxxxxx> escribió:

Hello,
I observe more and more performance issues with our application and
they started to show up after we've introduced a lot of SQL to our
system. We've did a lot of optimization but even after that we still
have some problems and I'm trying to understand what tools I can use
to see if hard drives are out bottleneck or maybe it is CPU.

System setup (from program/database perspective) is quite complicated.
We've moved from DDS to SQL tables(most tables) and MQT (materialized
query tables, biggest tables ) but programs were not changed and most
of them still use native I/O (but we have SQL behind because of RPG
Open Access and MQT/Indexes). I understand that we may have some
overhead because of this(on CPU) but for example MQT Updates/Insert
are quite slow but we use the for Read operation because chain
operation with sql behind was very slow without MQT. Of course we use SQL triggers in this setup.

We do not have EasyTier license and from what I've read it could tell
us if we could benefit from SSD. I've also found something about SSD
Analyzer (
http://www-01.ibm.com/support/docview.wss?uid=tss1prs3780) but only
for
7.1 and it look like it does not work on 7.3 (I could not see it as
collection in iNavigator

We have machine type 8286-41A (power8) with 3 LPARS which has few HDD
drives (raid 5) and StorWize 5010 with few HDD Drives. Unfortunately
we do not have VIOS and LPAR 1 (master) expose HDD to DEV LPAR and PROD LPAR.
This of course should and will be changed but to be honest I have no
idea how much performance we may get if we start use VIOS.

Now I'm totally lost which tools/commands could tell me if response
time from our HDD is weak point and this is why we have slow
read/write times and our CPU does nothing because it waits for HDD(and
we should buy few SSD for hot files). We have Performance Tool so I
can use collections services/performance monitor and then print one of
available reports but there are so many of them. I guess disk report can be used.

Do You have any advices what should I check here?


Filip
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