vmware esxi – Need to diagnose low frequency intermittent failure when logging on to Microsoft SQL Server

We have a deployment with roughly 10 Microsoft SQL Server 2017 (14.0.3335.7) instances running on 2 VMWare Virtual Machines, each running on different Dell servers. Each server has 1 main instance that processes 90+% of all connections and some other instances that serve other low traffic needs. The main servers both get hundreds of thousands of logins daily.

Among the hundreds of thousands, there are two sources of activity that are well monitored and measured. Each source targets a different main SQL server instance. The first is a job processing application server that runs roughly 1200 jobs overnight. The second is a job that runs once a minute all day and records results in a SQL server table.

Of these well measured process, we see 5-10 failures every night, all during the login process. There is no consistency in timing or which jobs fail.

The error message is very consistent. “A connection was successfully established with the server, but then an error occurred during the login process. (provider: SSL Provider, error: 0 – An existing connection was forcibly closed by the remote host.)”. The message comes from the .Net SqlConnection class during .Open().

I cannot find anything time correlated in firewall or SQL Server logs. My question is does anyone know how to get more information about what happens to cause this. It could be network packet drop, it could be SSL negotiation failure, it could have something to do with a certificate CRL download failure, or it could be something completely unexpected. I would like to get some SQL Server kernel-level-like debugging information that might give me a clue as to what is going on.

Any thoughts, tool references, or avenues to pursue would be appreciated.

encryption – Character frequency graph for cipher text

Monoalphabetic cipher is a substitution cipher in which for a given key, the cipher alphabet for each plain alphabet is fixed throughout the encryption process. For example, if ‘A’ is encrypted as ‘D’, for any number of occurrence in that plaintext, ‘A’ will always get encrypted to ‘D’.

source -> https://www.tutorialspoint.com/cryptography/traditional_ciphers.htm#:~:text=Monoalphabetic%20cipher%20is%20a%20substitution,get%20encrypted%20to%20’D’.

Here an example for how it can be decrypted with character frequency graph

Part of the plain text

Computer security, cybersecurity1 or information technology security (IT security) is the
protection of computer systems from theft or damage to their hardware, software or electronic
data, as well as from disruption or misdirection of the services they provide.
The field is growing in importance due to increasing reliance on computer systems, the
Internet2 and wireless networks such as Bluetooth and Wi-Fi, and due to the growth of “smart”
devices, including smartphones, televisions and the various tiny devices that constitute the
Internet of things. Due to its complexity, both in terms of politics and technology, it is also one
of the major challenges of the contemporary world.(3)

Part of the cipher text

XLNKFGVI HVXFIRGB, XBYVIHVXFIRGB1 LI RMULINZGRLM GVXSMLOLTB
HVXFIRGB (RG HVXFIRGB) RH GSV KILGVXGRLM LU XLNKFGVI HBHGVNH UILN
GSVUG LI WZNZTV GL GSVRI SZIWDZIV, HLUGDZIV LI VOVXGILMRX WZGZ, ZH
DVOO ZH UILN WRHIFKGRLM LI NRHWRIVXGRLM LU GSV HVIERXVH GSVB
KILERWV.
GSV URVOW RH TILDRMT RM RNKLIGZMXV WFV GL RMXIVZHRMT IVORZMXV
LM XLNKFGVI HBHGVNH, GSV RMGVIMVG2 ZMW DRIVOVHH MVGDLIPH HFXS
ZH YOFVGLLGS ZMW DR-UR, ZMW WFV GL GSV TILDGS LU “HNZIG” WVERXVH,
RMXOFWRMT HNZIGKSLMVH, GVOVERHRLMH ZMW GSV EZIRLFH GRMB
WVERXVH GSZG XLMHGRGFGV GSV RMGVIMVG LU GSRMTH. WFV GL RGH
XLNKOVCRGB, YLGS RM GVINH LU KLORGRXH ZMW GVXSMLOLTB, RG RH ZOHL
LMV LU GSV NZQLI XSZOOVMTVH LU GSV XLMGVNKLIZIB DLIOW.(3)
character frequncy graph for actual text
character frequncy graph for cipher text

Five cipher text characters with the highest frequency and speculate on the mapping to the
plaintext characters in the alphabet
Ciphertext plaintext
V E
G T
Z A
R I
I R

Basically this encryption is the reverse order of A-Z to Z-A
A-Z
B-Y
C-X

For this method, we need original text and ciphertext.

Script that reads rows and columns in a sheet and returns strings with frequency of occurrence

first time caller!

I have a single column that contains comma separated names (lots of names) — I am trying to find a script that can read the comma separated string entries in cell and give me a frequency count of each unique word. For example,

Dave
Jack
Anita, Peter
Peter
Kate, Noor
Noor
Peter
Peter, Dave

The expected output will be

Anita – 1
Dave – 2
Jack – 1
Kate – 1
Noor – 2
Peter – 4

Looking for any help. I know nothing about apps script and I am a novice sheets user too.

algorithms – How does each element in the output array of a DFT correspond to a specific frequency?

I have a basic understanding of the Fourier Transform, though I’m trying to use it in a program and I’m confused on the specifics. Based on source code I can find online, the DFT takes a set of samples/numbers, performs a summation for each term, and returns a set of these summations which is the same size as the input set. Suppose I have a periodic function. As I understand it, the output array should contain the amplitudes/weights of each frequency which sum to that function. What I can’t figure out is how each frequency is encoded in the array as just an index. In each example I read, we just assign a summation at each iteration of the inner loop to the next consecutive index in the output array. How are these indices indicative of which frequency they correspond to?

I’m attaching the source code I’m referencing to the bottom of this in case the website I linked to ever goes down.

import cmath
def compute_dft_complex(input):
    n = len(input)
    output = ()
    for k in range(n):  # For each output element
        s = complex(0)
        for t in range(n):  # For each input element
            angle = 2j * cmath.pi * t * k / n
            s += input(t) * cmath.exp(-angle)
        output.append(s)
    return output

drivers – Why is my CPU frequency driving crazy on Thinkpad X220 with i5-2540M Processor and Ubuntu 20.04

I encounter a strange behavior on my laptop, a Thinkpad X220 with i5-2540M CPU.I recently jumped from Windows 7 to Ubuntu 20.04, and I was hopping that everything would just perfectly work.
After just starting my computer, everything just work fine, in a smooth way and I’m the happiest man on earth.

But there is a moment, randomly and suddenlly where everything drastically slow down on my screen, and my mouse is jumping like if it was displayed at 1 frame per second. However, my CPU temperature and load is not high, the RAM usage is correct, etc. And when it begins, the CPU frequency is driving mad, going up and done quickly, without stabilizing.

Since my computer worked just perfectly when I was running Windows, I suppose it could be related to the linux drivers and the power and frequency management tools. Do you think it could be related ?

Did anyone encountered the same behavior running linux or specifically Ubuntu on its Thinkpad ?
Currently, my computer uses the intel_pstat driver in active mode but without the “Harware Managed P-states (HWP)” function available. Should I run it in passive mode (intel_cpufreq) ? Or even use the acpi-cpufreq driver instead ?

Other questions :

  • Would you know some tools that would allow me to precisely look at my CPU frequency ?
  • Do you know where I could my processor Model Specific Registers (MSR) to help me to configure my driver settings ?

By advance, thank you for your help. I am still a newbie concerning Linux. I installed it precisely to learn about it, but it looks like a hard beginning !
(And please excuse my english, my mother tongue language is french)

cpufreq – Unable to change the CPU frequency when on battery

There are multiple apps and scripts to change the CPU frequency. I have tried cpuf from this answer, cpufreq gnome extension, many CLI based apps and what not. But I am unable to change the frequency when I boot the laptop on battery.

But after switching on the AC adapter, I am able to change the frequency as per my wish. Basically when laptop is booted on battery, CPU frequency scaling is locked to 1.4Ghz, but after turning on the AC adapter, this lock is unlocked, and I can change the frequency as long as the laptop is not shutdown, or put to sleep, even after turning off the AC adapter.

CPU: intel i7-8750H
OS: Ubuntu 20.04 lts.

I used watch -n.1 "cat /proc/cpuinfo | grep "^(c)pu MHz"" command and frequeq gnome extension to check the CPU frequency.

I have quadruple booted by PC (Windows 10, Ubuntu 20.04, another Ubuntu 20.04, PopOS 20.04), and I have this problem on all, except Windows 10.

Good update frequency | Web Hosting Talk


Hi friends,

I have a server with 200-250 clients and cannot reboot server every day (because her webs will be down).

I contacted with CloudLinux support and they told me:

-All her software are updated with “yum update”: CloudLinux, Imunify360, Kernelcare, etc.
-Only need reboot server when update the Kernel, not when update other CloudLinux things (but with Kernelcare i can wait time because patch are applied in RAM).

I need know:

-What frequency you recommend me reboot the server?, ¿each 15 days, each month…?
-Anybody know if WHM/cPanel, LiteSpeed, Softaculous and JetBackup also updated when system use “yum update”?.

If in your experience recommend me other update method for servers please tell me.

Thank you very much.