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NBUF and BUFPAGES vs. Dynamic Buffer Cache

Elvin_Vega
Collector

NBUF and BUFPAGES vs. Dynamic Buffer Cache

Hello:

 

I have a cluster with 4 server. Actually they are configured to use NBUF and BUFPAGES. Is better to use the DBC(Dynamic Buffer Cache) than use the NBUF and BUFPAGES? Use the DBC increase performance? Also I want to lower the SWAP utilization. Where I should start looking?

 

The server set up are:

# uname -a
HP-UX B.11.23 U ia64 3314175231 unlimited-user license


# sysdef | grep -i "buf"
bufpages                 838445          -          0-           Pages   -
nbuf                    4418058          -          0-                   -


# kctune | grep -i "dbc_"
dbc_max_pct                          5  5           Immed
dbc_min_pct                          2  2           Immed

 

# glance

 Glance C.04.60.000             12:41:27   hpium3     ia64                                                    Current  Avg  High
--------------------------------------------------------------------------------------------------------------------------------
CPU  Util   S    SU                        U                                                                   | 32%   27%   36%
Disk Util   F   F                                                                                              |  5%    6%    9%
Mem  Util   S                SU                                  UB   B                                        | 60%   60%   60%
Swap Util   U                         UR                  R                                                    | 47%   47%   47%
--------------------------------------------------------------------------------------------------------------------------------
                                                         MEMORY REPORT                                              Users=    2
Event         Current   Cumulative   Current Rate   **bleep** Rate   High Rate
--------------------------------------------------------------------------------
Page Faults      1688         5209       366.9      248.0       391.9
Page In             0           64         0.0        3.0        66.7
Page Out            0            0         0.0        0.0         0.0
KB Paged In       0kb        256kb         0.0       12.1        89.6
KB Paged Out      0kb          0kb         0.0        0.0         0.0
Reactivations       0            0         0.0        0.0         0.0
Deactivations       0            0         0.0        0.0         0.0
KB Deactivated    0kb          0kb         0.0        0.0         0.0
VM Reads            0           11         0.0        0.5         1.3
VM Writes           3            6         0.6        0.2         0.6
Total VM :  34.9gb   Sys Mem  :  11.7gb   User Mem:  23.4gb   Phys Mem :  64.0gb
Active VM:  34.7gb   Buf Cache:   3.2gb   Free Mem:  25.7gb   FileCache:      na

 

Tips or recommendations are welcome. =)

 

Regards,

 

Elvin

 

5 REPLIES
Dennis Handly
Acclaimed Contributor

Re: nbuf and bufpages vs. Dynamic Buffer Cache

>Is better to use the DBC(Dynamic Buffer Cache) ...

 

It's probably much easier.

 

>I want to lower the SWAP utilization. Where I should start looking?

 

You buy more RAM or run less processes.  What does "swapinfo -tam" show?

Are you running a database on this machine?  Your dbc_max_pct seems small enough for that.

 

I don't see any page outs, so your swap is fine.

Elvin_Vega
Collector

Re: nbuf and bufpages vs. Dynamic Buffer Cache

Dennis Handly:

 

We are running IUM6.3 but that application have a database system using Solid. That may do a big impact on the DBC at 5% max?

 

This the output for the command "swapinfo -tam".

 

# swapinfo -tam
             Mb      Mb      Mb   PCT  START/      Mb
TYPE      AVAIL    USED    FREE  USED   LIMIT RESERVE  PRI  NAME
dev       16384       0   16384    0%       0       -    1  /dev/vg00/lvol2
reserve       -   16384  -16384
memory    65504   22427   43077   34%
total     81888   38811   43077   47%       -       0    -

Dennis Handly
Acclaimed Contributor

Re: nbuf and bufpages vs. Dynamic Buffer Cache

>This the output for the command "swapinfo -tam".

 

It looks like you have plenty of swap space at this time and you aren't actively swapping.

Elvin_Vega
Collector

Re: nbuf and bufpages vs. Dynamic Buffer Cache

Dennis:

 

Ok. But about the DBC. What about the values we got and the application we are running in the server. Is going to be need to increase DBC parameters?

 

Regards,

 

Dennis Handly
Acclaimed Contributor

Re: nbuf and bufpages vs. Dynamic Buffer Cache

>What about the values we got and the application we are running in the server. Is going to be need to increase DBC parameters?

 

If you have plenty of memory and you aren't using an Oracle DB, you can increase the DBC to see if it helps.