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Showing posts from April 8, 2020

Database Recovery Strategies

Be it a natural disaster striking your primary data center and obliterating all your databases or some technical error that brings it down, forcing you to consider moving your database to your backup DR (disaster recovery) location, the right disaster recovery strategy would definitely save the day. How do we accomplish this? Well, there are primarily three strategies, you can considering, depending upon your downtime tolerance level: Electronic Vaulting Remote Journaling Remote Mirroring Let us see what each one of them has in store for us: Electronic Vaulting These are essentially bulk transfers wherein the database backups are moved from the primary site to the remote (backup / DR) site via network There is a significant delay between the time you declare a disaster and the time to recover your database backups Entire Backup files are transferred Not suited for hot sites where the recovery should be instantaneous Remote Journaling These are much more frequent and faster than Electro...

RAID

Stands for Redundant Array of Inexpensive Disks (or Redundant array of Independent Disks) It is a data storage virtualization technology that combines multiple physical disk drives into logical units to ensure data redundancy and performance improvement The standard RAID levels including there features and the number of disks that ensure their functionality are : RAID levels Features Number of disks RAID 0 Striping At least 2 RAID 1 Mirroring At least 2 RAID 5 Striping with parity At least 3 but upto 16 RAID 6 Striping with double parity At least 4 RAID 10 Combining mirroring and striping At least 4 RAID types A bit more... RAID 0 : It improves the disk subsystem performance, but it does not provide fault tolerance RAID 1: It uses same disks which both hold the same data. If one disk fails, the other disk continues to operate as usual. RAID 5: It uses three or more disks with the equivalent of one disk holding parity information. If one disk fails, the RAID array will continue to oper...