Nowadays the most compact data carrier is undoubtedly a memory card (SD/MMC/MS and so forth) and USB flash drive. They have emerged relatively recently but have already made a huge breakthrough in development. Just a few years ago the capacity of such device was only 4 to 8 Mb, and today such devices can replace a small hard drive and its capacity reaches several Gigabytes. Though the problems you can face when working with such drives and cards are akin to the ones of HDD. For example, the majority of users have certainly faced the barriers when creating large capacity logical disks (everyone knows about the situation when FAT16 doesn’t allow creating a partition over 2 Gb. We face the same problem when working with flash drives.

Andrei Ivanov has written a remarkable article on data protection (Would you prefer tea with sugar or washing your hands with soap?).
The topic is of interest to me and I have been thinking about writing something similar for a long time.
To make a long story short, there are several levels of data protection and security:
- hardware;
- software;
- and organizational level.

Generally speaking, the division is fairly conventional and later I will provide examples of cross-level solutions.

Hardware level

To prevent hardware malfunctions any component at the hardware level is duplicated. The most common solution for this level is to have two power units and RAID group of several hard drives (arbitrary level, except zero level). This level solutions only help reducing or ruling out downtime caused by server hardware malfunction. That is:
- failure of hard drive ~ RAID controller rebuilds RAID group independently, no need of system administrator involvement. Service users won’t even notice anything.
- a user has deleted file or record in info. system ~ End of story! Hardware level is helpless here.
Solutions like VMware HA or VMware FT entirely refer to this level (especially HA).