When discussing availability of a service, it is common to hear the term “Five Nines” referring to a service being available 99.999% of the time but “Five Nines” are relative.
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In reality, none of those calculations are relevant because no one cares if a service is unavailable for 10 hours, as long as they…

Reporting projects are the kind of projects which never seem to end. After a couple iterations I’ve come to the following conclusions:

Absolutely no reports should run on a production database.
Moving/aggregating data from a production database to a reporting database using ETL tools prone to synchronization issues and pretty unreliable.
The best option is to set…

The following table shows the difference between 146GB RAID 5 IOPS/TB and 300GB RAID 10 IOPS/TB.
Each column represents a different Read percentage (the Write percentage is the inverse).
Negative numbers mean that for this Read percentage and IOPS requirement, RAID 10 gives more IOPS/TB of disk. Positive numbers mean that RAID 5 gives better…

A disk I have in a production machine went bad:
d4: Mirror Submirror 0: d14 State: Okay Submirror 1: d24 State: Needs maintenance Pass: 1 Read option: roundrobin (default) Write option: parallel (default) Size: 120850176 blocks…

Someone recently asked me how to setup redundant power for a rack of machines without relying on all the equipment to have dual power supplies.
The answer is called an Automatic Transfer Switch. Depending on the sensitivity of your equipment to momentary losses of power, you can choose between an Open Transition Transfer Switch and…