Inserting entry in .db file from Linux shell

March 4, 2023 Leave a comment

  • Create a text file containing necessary entries, e.g
[root@rac1 ~]# cat test.txt
ora.test.db
\92\c4\9dhard(global:uniform:ora.DATA.dg) pullup(global:ora.DATA.dg) weak(type:ora.listener.type, global:type:ora.scan_listener.type, uniform:ora.ons, global:ora.gns)\c4\c5hard(fg.DATA.DisksReady, global:uniform:ora.DATA.dg) pullup(fg.DATA.DisksReady, global:ora.DATA.dg) weak(type:ora.listener.type, global:type:ora.scan_listener.type, uniform:ora.ons, global:ora.gns)

Please note, this is a sample entry that was necessary in my case. You better know what should be there for your case.

  • Create output.db file from test.txt
[root@rac1 ~]# db_load -T -t btree -f test.txt output.db
  • Read data from output.db file to make sure that the entry is there using db_dump
[root@rac1 ~]# db_dump -p output.db
VERSION=3
format=print
type=btree
db_pagesize=4096
HEADER=END
 ora.test.db
 \92\c4\9dhard(global:uniform:ora.DATA.dg) pullup(global:ora.DATA.dg) weak(type:ora.listener.type, global:type:ora.scan_listener.type, uniform:ora.ons, global:ora.gns)\c4\c5hard(fg.DATA.DisksReady, global:uniform:ora.DATA.dg) pullup(fg.DATA.DisksReady, global:ora.DATA.dg) weak(type:ora.listener.type, global:type:ora.scan_listener.type, uniform:ora.ons, global:ora.gns)
DATA=END
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This system has no repositories available through subscriptions.

December 29, 2022 Leave a comment

Problem:

Enabling repos fails:

[root@app1 mari_scripts]# subscription-manager repos --enable rhel-7-server-optional-rpms \
>     --enable rhel-server-rhscl-7-rpms \
>     --enable rhel-7-server-devtools-rpms
This system has no repositories available through subscriptions.

Solution:

Run the following:

[root@app1 mari_scripts]# subscription-manager attach --auto

Installed Product Current Status:
Product Name: Red Hat Enterprise Linux Server
Status:       Subscribed

Reenable repositories:

[root@app1 mari_scripts]# subscription-manager repos --enable rhel-7-server-optional-rpms     --enable rhel-server-rhscl-7-rpms     --enable rhel-7-server-devtools-rpms
Repository 'rhel-7-server-optional-rpms' is enabled for this system.
Repository 'rhel-7-server-devtools-rpms' is enabled for this system.
Repository 'rhel-server-rhscl-7-rpms' is enabled for this system.

Filed under Linux, OS Tagged with , , , ,

This system is not registered with an entitlement server. You can use subscription-manager to register.

December 23, 2022 Leave a comment

Problem:

Trying to install/update/search packages using yum fails:

[root@app1 mari_scripts]# yum whatprovides clang
Loaded plugins: amazon-id, product-id, search-
              : disabled-repos, subscription-manager,
              : versionlock
This system is not registered with an entitlement server. You can use subscription-manager to register.

Excluding 1 update due to versionlock (use "yum versionlock status" to show it)
No matches found

Actually, it is still searching for the package, but the messages, in the beginning, are frustrating. So let’s just solve it.

I tried to register the system, but here also did a mistake, I have indicated the email address in the username:

[root@app1 mari_scripts]# subscription-manager register
Registering to: subscription.rhsm.redhat.com:443/subscription
Username: <my RHEL username, email address>
Password:
HTTP error (401 - Unauthorized): Invalid username or password. To create a login, please visit https://www.redhat.com/wapps/ugc/register.html

I was able to login through browser but could not register the system with it.

Solution:

After searching a lot and losing my time, I came accross one thread where the person was saying that account id should be used instead of email address. By the way, later found out the the RHEL also was mentioning that in one of its articles:

“Please use your Login ID/User ID instead of your Email Address to register your RHEL machine.”

So go to you account settings from browser and see what is your Login name, register the system with it:

[root@app1 mari_scripts]# subscription-manager register
Registering to: subscription.rhsm.redhat.com:443/subscription
Username: <myloginnamegoeshere>
Password:
The system has been registered with ID: 22328e0c-f672-4489-939b-529a9d2875a1
The registered system name is: app1.mycompany.mydomain

Filed under Linux, OS Tagged with , , ,

Comparing speed between 2 cores vs 1 multi-threaded core

December 14, 2022 Leave a comment

My colleague at Flashgrid, Mikhail Velikikh did a very interesting test case, and I want to share it with you.

He tested two Azure VMs:

DS2_v2 – 2 cores with 1 thread each
D2S_v5 – 1 core with 2 threads

So as you see the total number of threads is the same, and also both of them are Intel Xeon 8370C. The test showed that VM with 2 cores is processing more events than VM with 1 core and 2 threads.

The command used for this test is the following:

# curl --noproxy '*' -H Metadata:true -s -f "http://169.254.169.254/metadata/instance/compute?api-version=2017-12-01" | jq -r '.vmSize'

# lscpu

# sysbench --threads=2 cpu run

curl and lscpu commands are just showing current VM size and CPU info.

The output for DS2_v2 (processed 4282.14 events per second):

+ curl --noproxy '*' -H Metadata:true -s -f 'http://169.254.169.254/metadata/instance/compute?api-version=2017-12-01'
+ jq -r .vmSize
Standard_DS2_v2
+ lscpu
Architecture:                    x86_64
CPU op-mode(s):                  32-bit, 64-bit
Byte Order:                      Little Endian
Address sizes:                   46 bits physical, 48 bits virtual
CPU(s):                          2
On-line CPU(s) list:             0,1
Thread(s) per core:              1
Core(s) per socket:              2
Socket(s):                       1
NUMA node(s):                    1
Vendor ID:                       GenuineIntel
CPU family:                      6
Model:                           106
Model name:                      Intel(R) Xeon(R) Platinum 8370C CPU @ 2.80GHz
Stepping:                        6
CPU MHz:                         2793.436
BogoMIPS:                        5586.87
Hypervisor vendor:               Microsoft
Virtualization type:             full
L1d cache:                       96 KiB
L1i cache:                       64 KiB
L2 cache:                        2.5 MiB
L3 cache:                        48 MiB
NUMA node0 CPU(s):               0,1
Vulnerability Itlb multihit:     KVM: Mitigation: VMX unsupported
Vulnerability L1tf:              Mitigation; PTE Inversion
Vulnerability Mds:               Mitigation; Clear CPU buffers; SMT Host state unknown
Vulnerability Meltdown:          Mitigation; PTI
Vulnerability Mmio stale data:   Vulnerable: Clear CPU buffers attempted, no microcode; SMT Host state unknown
Vulnerability Retbleed:          Not affected
Vulnerability Spec store bypass: Vulnerable
Vulnerability Spectre v1:        Mitigation; usercopy/swapgs barriers and __user pointer sanitization
Vulnerability Spectre v2:        Mitigation; Retpolines, STIBP disabled, RSB filling, PBRSB-eIBRS Not affected
Vulnerability Srbds:             Not affected
Vulnerability Tsx async abort:   Mitigation; Clear CPU buffers; SMT Host state unknown
Flags:                           fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ss ht syscall nx pdpe1gb rdtscp lm constant_tsc rep_good nopl xtopology cpuid pni pclmulqdq ssse3 fma cx16 pcid sse4_1 sse4_2 movbe popcnt aes xsave avx f16c rdrand hypervisor lahf_lm abm 3dnowprefetch invpcid_single pti fsgsbase bmi1 hle avx2 smep bmi2 erms invpcid rtm avx512f avx512dq rdseed adx smap clflushopt avx512cd avx512bw avx512vl xsaveopt xsavec xsaves md_clear
+ sysbench --threads=2 cpu run
sysbench 1.0.20 (using bundled LuaJIT 2.1.0-beta2)

Running the test with following options:
Number of threads: 2
Initializing random number generator from current time


Prime numbers limit: 10000

Initializing worker threads...

Threads started!

CPU speed:
    events per second:  4282.14

General statistics:
    total time:                          10.0003s
    total number of events:              42832

Latency (ms):
         min:                                    0.46
         avg:                                    0.47
         max:                                    1.38
         95th percentile:                        0.47
         sum:                                19988.62

Threads fairness:
    events (avg/stddev):           21416.0000/28.00
    execution time (avg/stddev):   9.9943/0.00

The output for D2s_v5 (processed 3131.14 events per second):

+ curl --noproxy '*' -H Metadata:true -s -f 'http://169.254.169.254/metadata/instance/compute?api-version=2017-12-01'
+ jq -r .vmSize
Standard_D2s_v5
+ lscpu
Architecture:                    x86_64
CPU op-mode(s):                  32-bit, 64-bit
Byte Order:                      Little Endian
Address sizes:                   46 bits physical, 57 bits virtual
CPU(s):                          2
On-line CPU(s) list:             0,1
Thread(s) per core:              2
Core(s) per socket:              1
Socket(s):                       1
NUMA node(s):                    1
Vendor ID:                       GenuineIntel
CPU family:                      6
Model:                           106
Model name:                      Intel(R) Xeon(R) Platinum 8370C CPU @ 2.80GHz
Stepping:                        6
CPU MHz:                         2800.000
CPU max MHz:                     2800.0000
CPU min MHz:                     800.0000
BogoMIPS:                        5586.87
Virtualization:                  VT-x
Hypervisor vendor:               Microsoft
Virtualization type:             full
L1d cache:                       48 KiB
L1i cache:                       32 KiB
L2 cache:                        1.3 MiB
L3 cache:                        48 MiB
NUMA node0 CPU(s):               0,1
Vulnerability Itlb multihit:     Not affected
Vulnerability L1tf:              Not affected
Vulnerability Mds:               Not affected
Vulnerability Meltdown:          Not affected
Vulnerability Mmio stale data:   Vulnerable: Clear CPU buffers attempted, no microcode; SMT Host state unknown
Vulnerability Retbleed:          Vulnerable
Vulnerability Spec store bypass: Vulnerable
Vulnerability Spectre v1:        Mitigation; usercopy/swapgs barriers and __user pointer sanitization
Vulnerability Spectre v2:        Mitigation; Retpolines, STIBP disabled, RSB filling, PBRSB-eIBRS Not affected
Vulnerability Srbds:             Not affected
Vulnerability Tsx async abort:   Not affected
Flags:                           fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ss ht syscall nx pdpe1gb rdtscp lm constant_tsc rep_good nopl xtopology tsc_reliable nonstop_tsc cpuid aperfmperf pni pclmulqdq vmx ssse3 fma cx16 pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand hypervisor lahf_lm abm 3dnowprefetch invpcid_single tpr_shadow vnmi ept vpid ept_ad fsgsbase tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid rtm avx512f avx512dq rdseed adx smap avx512ifma clflushopt clwb avx512cd sha_ni avx512bw avx512vl xsaveopt xsavec xgetbv1 xsaves avx512vbmi umip avx512_vbmi2 gfni vaes vpclmulqdq avx512_vnni avx512_bitalg avx512_vpopcntdq la57 rdpid fsrm arch_capabilities
+ sysbench --threads=2 cpu run
sysbench 1.0.20 (using bundled LuaJIT 2.1.0-beta2)

Running the test with following options:
Number of threads: 2
Initializing random number generator from current time


Prime numbers limit: 10000

Initializing worker threads...

Threads started!

CPU speed:
    events per second:  3131.14

General statistics:
    total time:                          10.0005s
    total number of events:              31318

Latency (ms):
         min:                                    0.34
         avg:                                    0.64
         max:                                    1.59
         95th percentile:                        0.64
         sum:                                19996.86

Threads fairness:
    events (avg/stddev):           15659.0000/22.00
    execution time (avg/stddev):   9.9984/0.00

Filed under Linux, OS Tagged with , , ,

Terminal window xterm is not displayed in VNC

June 15, 2022 Leave a comment

Problem:

After installing/starting the tiger VNC server, and connecting using VNC Viewer terminal window is not displayed.

# yum install tigervnc-server

Solution:

Install xterm:

# yum install xterm

Kill old VNC process and start again:

$ vncserver -kill :1
$ vncserver -geometry 1024x1024

Reconnect using VNC viewer, terminal should be displayed automatically.

Filed under Linux, Oracle Enterprise Linux, OS Tagged with , ,

Install Google Chrome on Linux 7.9 using terminal

April 21, 2022 Leave a comment

There are several ways to do that, I found the simplest (I hope so) and want to share it with you:

0. Create repo file:

# vi /etc/yum.repos.d/google-chrome.repo

[google-chrome]
name=google-chrome
baseurl=https://dl.google.com/linux/chrome/rpm/stable/x86_64
enabled=1
gpgcheck=1
gpgkey=https://dl.google.com/linux/linux_signing_key.pub

1. Enable repo ol7_optional_latest for vulkan dependency:

# yum-config-manager --enable ol7_optional_latest

2. Install google-chrome-stable package:

# yum install google-chrome-stable -y

3. Run:

$ google-chrome

Or in the background:

$ google-chrome &

The window will come up in VNC or X Window whichever you’ve configured before.

Filed under Linux, Oracle Enterprise Linux, OS Tagged with , , , ,

Change default kernel using grubby Tool

March 22, 2022 Leave a comment

There are several ways to fulfill the same task, I am providing one of them.

  1. Check the information about currently loaded kernel:
# uname -r
5.4.17-2036.101.2.el7uek.x86_64

2. Find all available kernels in your system and locate their index number:

# grubby --info=ALL
index=0
kernel=/boot/vmlinuz-5.4.17-2036.101.2.el7uek.x86_64
args="ro console=tty1 console=ttyS0,115200n8 earlyprintk=ttyS0,115200 rootdelay=300 numa=off transparent_hugepage=never net.ifnames=0"
root=/dev/mapper/rootvg-rootlv
initrd=/boot/initramfs-5.4.17-2036.101.2.el7uek.x86_64.img
title=Oracle Linux Server 7.9, with Unbreakable Enterprise Kernel 5.4.17-2036.101.2.el7uek.x86_64

index=1
kernel=/boot/vmlinuz-3.10.0-1160.42.2.el7.x86_64
args="ro console=tty1 console=ttyS0,115200n8 earlyprintk=ttyS0,115200 rootdelay=300 numa=off transparent_hugepage=never net.ifnames=0"
root=/dev/mapper/rootvg-rootlv
initrd=/boot/initramfs-3.10.0-1160.42.2.el7.x86_64.img
title=Oracle Linux Server 7.9, with Linux 3.10.0-1160.42.2.el7.x86_64

index=2
kernel=/boot/vmlinuz-0-rescue-d3dd3af16fd242cebb997c6041d68ad3
args="ro console=tty1 console=ttyS0,115200n8 earlyprintk=ttyS0,115200 rootdelay=300 numa=off transparent_hugepage=never net.ifnames=0"
root=/dev/mapper/rootvg-rootlv
initrd=/boot/initramfs-0-rescue-d3dd3af16fd242cebb997c6041d68ad3.img

3. Check currently loaded kernel index using grubby tool (actually, we could find the same from 1st and 2nd steps, but let’s do one more time):

# grubby --default-index
0

4. Change the default kernel, in my case I want to set it to vmlinuz-3.10.0-1160.42.2.el7.x86_64 and it’s index number is 1:

# grubby --set-default 1

5. Reboot the system and check the kernel again:

# reboot
# uname -r
3.10.0-1160.42.2.el7.x86_64

Filed under Linux, Oracle Enterprise Linux, OS Tagged with , , ,

Useful tools for analyzing OS diagnostic data

February 12, 2022 Leave a comment

Filed under DB, Linux, Oracle Enterprise Linux, OS Tagged with , , , , , , , ,

Can fs.aio-max-nr be changed on a live system?

December 17, 2021 Leave a comment

Short answer:

Yes, it can be changed without impacting the business operations.
Oracle source: Doc ID 2269728.1
RHEL source: https://access.redhat.com/solutions/437043

========================Additional information========================

Additional explanation, why you may need to change that value.

Problem:

Alert log shows:

ORA-27090: Unable to reserve kernel resources for asynchronous disk I/O
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3
Additional information: 128
Additional information: 139817340277512

Reason:

The problem is caused by a lower than recommended value for aio-max-nr. The current value is 1048576, but recommended is 3145728.

Solution:

Set fs.aio-max-nr to 3145728 in /etc/sysctl.conf. 

# grep fs.aio-max-nr /etc/sysctl.conf
fs.aio-max-nr = 3145728

Make a new value effective:

# sysctl -p  /etc/sysctl.conf

Verify the new value:

# sysctl -a|grep fs.aio-max-nr
fs.aio-max-nr = 3145728

Filed under Linux, Oracle Enterprise Linux, OS Tagged with , , , , ,

Add new virtual machine in VBox and install Oracle Linux

June 19, 2021 Leave a comment

Intro:

This blog post belongs to my student at Business and Technology University Ivane Metreveli, thank you Ivane for participating in this project.

  1. First of all, you need to download Oracle Linux iso file from edelivery.oracle.com or from oracle.com. After that, run VirtualBox, click New button and create new virtual machine:

2. Set Name of the Virtual Machine and select operation system as follows, click Next

3. Select appropriate RAM amount, 3GB RAM is recommended for normal processing, click on Next button and jump to next step

4. Now, Select Create a virtual hard disk now option and click Create button

5. Select VDI(virtualbox Disk image)

6. Select Dynamically allocated if you don’t want take hard disk space immediately

7. Select file size (disk size for VB) and the location, click Create button to finish virtual machine creation process

8. Virtual machine is already is created. Before we open/start VM, we load iso file in the machne, click Settings and follow me

9. Navigate to Storage and click CD icon,  on the right side of the window, under attributes, click CD icon and add virtual machine’s .iso file.

10. After that, you can click start button

11. Select .iso files or click folder icon and open folder where .iso file is located, select it and click start

12. Next step is OS installation process, here you select Install Oracle linux 7.6 and click enter to start installation process:

13. Select system language and click continue

14. Select installation destiantion

15. Select the disk where you want to install system. You can select virtual disk, that you have created in the previous step or add a new one. Select disk and click Done button;

16. Now all parameter is ready. Click Begin Installation and wait for finishing the process

17. Set password and click Done

18. Installation is in progress, need to wait more

19. Installation proess is finished, click Roboot button and move to the next step:

20. Installation is finised now, you can start working with Oracle Linux:

Filed under Linux, OS, VirtualBox Tagged with , ,

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