My Linux Stories

Issue Have you ever felt that write to a partition has become relatively slower than previously?? Ever wondered how to debug such kind of issues Then this post is for you. Useful commands are lsblk iotop iostat dd Check the partition type using  df -Th Debugging dd command is used to emulate disk write to the device.  In this example we are just writing the stream of  /dev/zero of size 1G to our partition. A key observation was that the real time was way higher than sys and user time combined. for i in {0..60}; do time dd if=/dev/zero of=/data/1GB.bin bs=1G count=1; done output real 31m27s user 00m00s sys 00m806s dd process was observed to be in uninterruptible sleep (D) state using the following command for the most part of the time as the above command was under execution. iotop (run as a root user) showed that there was no disk activity on any of the disks on the device. Few takeaways: /dev/zero produces a continuous stream of NULL (

Introduction If you have ever installed Mongo 3.* version and worrying as to how to upgrade it to Mongo 4.x. Then this story is for you, Mongo has made the upgrades comparatively easy. This story is a brief overview as to how to upgrade Mongo and it is divided into three segments Identification While Migrating Databases from one node to another using mongodump --host sourcehost:27017 --db client_c_n --archive | mongorestore --host targethost:27017 --archive We landed into Unrecognized field 'snapshot'. mongo this error. Debugging We saw that there is a version mismatch as in source host being 4.2.x and target being 3.6.17 between both the mongo servers. Now we have to take an immediate step to upgrade mongo and maintain the same version of mongo across the nodes. So that the dumps can be transferred between nodes. Solution Please note that you can update mongo DB only on Stepwise. For instance, To upgrade from a version earlier than the 3.6-series, yo

In this post we will start understanding an interesting topic in python i.e Unit_tests and most important of all while developing any software is understanding the actual use-case and be clear with the tests to be covered to verify the working of the use-case. Unit tests are that type of tests which are not considered as functional tests rather, It is used to do some basic testing of python definitions by sending some fake parameters to the actual definitions in source code and assert the expected values Say suppose now u have written a code to test whether a number is a prime or not we send some random value and check whether we get the expected value or not. So, our use-case is to check whether the number gave by user is prime or not? So, the tests to be checked are  - Composite numbers shouldn't be returned as prime.  - Negative numbers mustnot be considered as a prime number.  - check when a prime number is given by user it returns True. mkdir test_1 &&

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