Data Security and Backups

Friday 23 December 2011

What is Data Recovery

I have been discussing in my previous posts related to Data Backups. I shall be throwing some light on Data Recovery which is the reason we do should be doing Data Backups. Data Backup should actually be called recovery solutions because backups come to rescue when disaster strikes.
In the most simplest terms, “Data Recovery” can be described as process of recovering data from a hard disk drive, CD-Drive, USB sticks, external disks or any other media where the respective has failed.
There are many ways data can be stored:
§  Hard disk Drives
§  CDs or DVDs
§  External Disks
§  USB sticks
§  RAID Servers

No matter how reliable these products may be but any electronic device can fail to function. Over and above, there are other reasons for loss or inaccessibility to data. To name a few:

§  Accidental deletion of data
§  Mishandling of devices
§  Forgot passwords
§  Natural disasters like floods, fire
§  Formatting a disk

When data cannot be restored through any normal process, then comes “Data Recovery” process. Data recovery is the process to access safe, reliable data from that device.
The Data Recovery Process
Data Recovery can be simple in many cases and can be complex in certain cases. However any data recovery requires following general steps:
1.    Identity the media and find out the amount of damage. Many data recovery solutions companies can analyze and let you know if they can recover data. If the media is intact but maybe you have forgotten password for the device [like on a USB stick] you can try to recover using 3rd party software’s.
2.    Estimate how much work shall be involved, how much data can be recovered and what cost shall be involved. Data Recovery companies might give you a flat-rate, but try to go in more detail. Does the data recovered is important or your vital data is still unavailable.
3.    Analyze the recovered data to be sure the data is useable and matches your records. Make more than one copy of recovered data.
4.    Return: Always get your damaged media back. No matter what state it is.
5.   Check the reason what caused the media to be damaged. Repair any electrical or mechanical reason e.g. power supply for hard disk failure.

I have come across many SMBs who want to implement backup system but unfortunately it is on a low priority, whereas it should be the other way. Only they take it seriously when disaster strikes and they need to run all around to get data recovered from nowhere
I shall be giving an example of one of my clients, which was a pharmaceutical company. Pretty healthy profit making company. One fine day, their Server Hard disk drive crashed. Unfortunately, the backup system in place was manual system and some one had done backup about 2 weeks back. They were in a situation where in from no where they had to recover data from that hard disk. They had contacted number of consultants, paid huge amount of money but had no go. Ultimately they send their hard disk overseas, where one company stated data can be recovered, it took 2 weeks of time and ofcourse price was huge, but with no option they had to agree to that. Their data was recovered but had to go thru lots of hassle.
I bet you backup solution if implemented would have been much cheaper solution and the amount of time in terms of value is unmeasurable.
To summarize, if backup has been done and that too on regular basis, you are guaranteed to recover your data.

Tuesday 13 December 2011

What are Synthetic Backups?


A synthetic backup is identical to a regular full backup in terms of data, but it is created when data is collected from a previous, older full backup and assembled with subsequent incremental backups. The incremental backup will consist only of changed information.

Let’s take an example to understand:


Full Backup
1st December
1024 MB
Incremental Backup
5th December
200 MB
Incremental Backup
9th December
300 MB


A synthetic backup is needed if the backed up file needs copying as a single backup entity, or if it needs restoring. The contents of a synthetic backup differ depending upon the date chosen.
In our example two synthetic backups could be produced: one for 5th December; and one for 9th December. The data they contain would be different; the 5th December synthetic backup would not contain any changes to the file subsequent to that, whereas the 9th December synthetic backup would.


Information to know regarding Synthetic Backup


1.     It helps reduce the resources needed to backup. A full backup will require a set of server cpu cycles, some network bandwidth and backup media space. Each time you do a full backup you would need the same level of these three resources. By running an incremental backup you need only a fraction of the server CPU cycles, network bandwidth and additional backup media space. That reduces the backup window, the time needed to run the backup, considerably

2.     Incremental Backups increases the time needed for a restore because now a restore would need to return to the user the original backup file and all subsequent incremental backup files, and then the restored file needs re-building to merge in each incremental backup file's data. It takes more time, uses more server cycles and network bandwidth.

3.     By consolidating the original backup file and incremental backup files into a single Synthetic Backup the restore speed is faster because just one file now needs streaming to the user. Also the server CPU cycles needed for the restore are cut back.

4.     Synthetic full backups are media-based; they read backup data from one media and simultaneously write (restore) the result to the new active media within the same media group. As a result, synthetic full backups require that at least two media drives for the same storage policy be available at the time the job is started.
  1. Synthetic full backups consolidate data; they do not back up data from the client computer. You should therefore use synthetic full backups in addition to and not in place of any regularly scheduled incremental or differential backup jobs.