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Data preservation and recovery - the basics

Data preservation basics
STOP PRESS. After a recent problem with a stand-alone RAID (mirror) system I can no longer recommend these boxes (when one drive fails there's almost no indication of a problem until the other one also fails). See at end below

Can my PC's directory be so corrupted that I loose all my data ?

Not any more. Microsoft's NTFS format is extremely 'robust' and it is highly unlikely you will ever suffer from a 'corrupted' directory - unlike memory cards (CF, SDHC etc.) and USB 'sticks' etc. which still use the FAT32 format.

FAT32 is one reason to avoid those 'joke' plug-in USB 'backup' drives. Using a FAT32 directory structure means the so-called 'backup' is about 100x less reliable than the drive inside your computer ! Another reason to avoid them is that FAT32 will not support files over 4Gb ... which is not much good if your want to backup your movie collection

FAT32 corruption is so common that you can find any number of Open Source utilities that can recover data from a memory card and USB stick with a corrupted directory (see later).

What are the main reasons for data loss today ?

Mainly, accidental deletion and hard drive failures. The risk of file corruption caused by virus / root kits / Trojans (and your attempts to wipe them out) is quite low, and, if you follow my suggestions in How to avoid virus infections, you will have protected yourself against this already.

How can I protect myself against accidental deletion ?

A1. First, DO NOT empty your 'Recycle bin' every few minutes or even every day. Once a week, when your physical trash bin goes out, is often enough. That way, 99 times out of 100 when you realise you have deleted a file by accident it will still be sitting in the Recycle Bin for you to 'restore'.

There are Open Source 'undelete' software utilities that can still recover your files after you 'empty' the Recycle Bin, SO LONG AS YOU STOP USING THE PC IMMEDIATELY. The best can be 'written' to a bootable CD (so you won't have to risk overwriting your files when Windrows 'reboots').

Be aware that some well 'recommended' software (such 'NTFSundelete') is neither Open Source nor 'free' - and whilst such software may (always ?) claim it can recover your files, it will only actually try to do so after you pay the registration fee :-). Beware that much commercial software is advertised as 'Free Download' - this does not make it free to use, although sometimes you might get a feature reduced 'free trial'. If it does not say Open Source 'on the tin', expect to be held to ransom ..

Warning - when you delete files on a 'Network Share', they are NOT 'saved' to the Recycle Bin. So be extra careful with files on 'shares'

A2. Next, it's good idea to 'write protect' vital documents / music tracks / photos / movies etc. by 'right clicking', selecting Properties and changing the 'Attributes' of the files to 'Read Only'. You do this at the 'folder' level (i.e. make the folder and everything below it Read Only), however if you want to add new files to the folder you will need to 'unset' the Read Only on the folder itself (only)

Clever people will be aware that you can 'control' who can access files by changing the folder's 'Security' properties. The problem is, if you set a folder to 'deny' a user 'write' access (to prevent them deleting files) it also stops them adding files !

An alternative to manually setting files to 'Read only' is to run a 'script' (.cmd file) every so often (using Task Scheduler) that will automatically change the attributes of all the files found in specific ('watched') folders to 'read-only' (see Next>> page).

A3. When using any application (MS Office etc) to edit an important document, use 'SAVE AS' with a new file named 'version' every hour or so - eg. you could 'Save As' "My vital doc Issue 2.1" with the new name eg. "My vital doc Issue 2.2" etc.

A4. Finally, make regular backups of all your important files to another 'drive' (ideally a Network Server or NAS - see Building your own Home Server (NAS)).

Are hard drive failures inevitable ?

Yes, all hard drives are 'guaranteed' to fail one day - and that day is usually just after the end of the 5 year warranty :-). You can extend the life of your hard drives by keeping them cool and avoiding frequent on-off, on-off, on-off cycles.

Laptop hard drives run hot and, when you are running on batteries, they are constantly being 'spun down' only to be kicked back into life a few minutes later. Laptop drives thus have shorter lives and this is reflected in the manufacturers guarantee (3 years, or even less, is usual)

Interestingly, as drive capacity has increased beyond 2TB, the standard warranty period has decreased - some manufacturers now offer drives with warranties as little as 1 year !!!

How do I avoid loosing all my data when a hard disk fails ?

You configure 2 hard drives as a RAID 1 (Mirror). This means that you will have two drives containing identical data. When one fails, you will still be able to access all your data from the other one.

This is explained in detail on my How to setup RAID page.

Do I need special Hardware to run a RAID system ?

A1. No, Microsoft has built software RAID Mirror capability into all it's Operating Systems. However only the 'Server' versions have this capability 'enabled' by default (plainly Microsoft does not believe that home users have anything worth saving). Fortunately it is relatively easy to enable RAID (you have to make some simple text changes to 3 of your 'system' files).

You might wonder at Microsoft's take on this. Well plainly they will suggest it's 'illegal'. I take the view that I have licensed the full functionality of the software provided on the CD and as RAID functionality is built into the Operating System, I see choosing to enable it as no different from choosing to disable some of Microsoft's more useless 'Services' or otherwsie choosing to remove 'parts of the Operating System' that I have no use for (such as MSIE).

A2. Some motherboards have built-in Hardware RAID capability. The drawback is that if your motherboard fails you may be unable to recover data from the RAID.

Motherboard RAID chip-sets are usually made by Intel - so long as a replacement motherboard has the same chip-set it should 'recognise' your RAID set - but don't count on it. If (like most of us) you purchased a PC manufactured by one of the major 'OEMs' (eg Dell, HP), then you MUST stick to the same manufacturer's motherboard (your OEM Windows Licence is tied to the motherboard manufacturer, so a Dell RAID set is not going to boot on a HP motherboard (and vice-versa) - again, see later)

What else can I do to preserve my data ?

A1. You can perform regular backups to another disk or other media. Unlike RAID, this will also protect you against unintended deletion. For the ultimate in protection, install a Home Server or NAS device with multi-Terra-byte RAID storage.

A2. To preserve your System , you can install and use disk 'imaging' or 'cloning' software. I now recommend the very excellent DriveImage, however you should be aware that creating a system image will take approx 1 Hr per 100Gb.

See also my overview of Disk Imaging Software.

What 'other media' could I use for backing up ?

A1. If you have room in your computer, your could fit another hard disk drive just for backups. If you have a spare 5.25" mounting position at the front, consider using 'exchangeable' disk packs (although you should be aware that you may have to modify the 'opening' at the front to the full 5.25 form factor size as many 'fascia' plates are designed for CD/DVD tray opening not full sized drive removal).

If you don't have a 'spare' position, consider replacing the CD/DVD drive with an exchangeable pack / mobile caddy disk housing. The DVD drive can be placed into a USB housing (USB2 data rates are perfectly OK for reading & writing CD/DVD's).

A2. DVD's are only usable 'for backups' of a few Gb's of data - even Blu-Ray disks store less than 20Gb - however DVD's have the advantage that they can't be accidentally 'overwritten' - and data on a DVD might well survive even when the rest of your computer does not (eg power surge, lightning strike, fire).

A3. Tape systems may still be in use in some companies, however the tapes are more expensive 'per Mb' than hard disks (and much less reliable). Don't waste your time with tapes, even if a drive is offered 'for free'.

How do I protect my 'User Profile' ?

Windows XP seems quite good at corrupting your 'User Profile' (in C:\Documents and Settings\{your user name}\). Your 'Profile' contains the contents of your desktop (icon layout and contents of every folder on the desktop) and your 'My Documents' folder tree as well as your 'SID' (Security ID) and 'access rights' etc. etc.

You can get XP to 'auto-backup' your user 'profile' (this may even help to reduce the Gb's of 'temp' files that accumulate unnoticed in the C:\Documents and Settings\{your user name}\Local Settings\Temp folder etc.)

The trick is to 'pretend' that the 'local' user profile (the one in C:\Documents and Settings\{your user name}\) is a "roaming profile". Normally this is used by employees who 'hot desk' i.e. log-in from any computer that happens to be free = so when they log-in the computer has to 'fetch' their profile from the Company 'server' - and when they 'log out' any changes have to be saved back to the server

However it turns out you don't actually need a Server = it also works if you just 'point' at a different drive letter !

To use this trick, you start by making a 'remote copy' of your existing profile.

Log in using a different account (any will do so long as it has 'Administrator' rights). Create a folder on a different drive (eg D:) ready to store the 'back-up' (eg D:\PROFILES).

Right click 'My computer' and select 'Properties'. In the System Properties dialog box, select the Advanced tab and then click the Settings button in the User Profiles box.

From the User Profiles window, select (highlight) the profile of the user 'Name' you wish to 'back-up' and click the 'Copy To' button. Type in (or Browse to) the name of a folder your created above (eg D:\PROFILES).

Once you have a 'back up' copy of the users profile, you then have to modify the user account settings to make use of it

Use 'Start', 'Run', 'compmgmt.msc' to launch the computer Management console. In System Tools, expand the Local Users and Groups and open the 'Users' folder. Next, double-click on the user account name you wish to 'back-up' and select the Profile tab. In the Profile Path text box, enter the path to the 'remote copy' you created above (eg D:\PROFILES)

Linking the user account to the 'back-up' means that user account starts using a 'roaming profile'. Next time that account is 'logged in' the contents of the 'roaming profile in D:\PROFILES) will be copied to the local profile (c:\Documents and Settings\). When the account is 'logged off' any changes are copied from the local profile back to the 'remote' profile.

The profile back-up process is not a simple file copy .. it will 'detect' any problems with the local profile and not 'overwrite' the remote one .. and since the local profile is always replaced (each time you log on) this (should) guarantee that you will never see the 'your profile is corrupt' error again

What if Windows says 'profile is corrupt' and I don't have a back-up ?

When XP discovers your local profile is corrupt (when you log-on) it will create a 'temporary' profile (based on the 'all users') and continue the log-in. The original 'corrupt' profile still exists in C:\Documents and settings\{your user name}. This can usually 'recovered' by using the profile 'Copy to' function in the System Properties dialog box

You can't replace your 'own' (i.e. the 'live') user profile .. further, the 'corruption' is almost invariably associated with the user 'account' itself and not the actual profile data. So you will need to use an Administrator account (let's call it 'admin') to set-up a new account (to replace the 'corrupted' one) and then do a profile copy

So although you can 'recover' the profile, you do so by creating a replacement user account. So you will loose the existing users 'encrypted' folders and ALL 'passwords' etc. that have been 'saved' by Microsoft applications (such as MSIE, Outlook etc.). You thus need to 'decrypt' any encrypted folders (and locate and write down any passwords etc) before deleting the old account (see below).

See Microsoft web page for how to backup your Outlook Express address book and email folders

Log-in using admin. Set-up a replacement account. Log-off admin, log on with the replacement account so Windows generates a 'default' profile.

Log-off the replacement account, log-on as admin, use System Properties to select the 'corrupt' profile and use 'Copy To' to copy it over the 'replacement' account's default profile (in C:\Documents and Settings). If this fails, see below.

If the 'Copy To' succeeds, log-off admin, log-on as replacement and check you have your desktop & all your files etc. back. If all is OK you can delete the 'corrupted' user account

If the profile 'Copy to' fails, the reason is likely one of the 3 'Ntuser' files in the actual profile has become so corrupt that the MS software can't cope. You can 'drag and drop' the files from the 'original user' profile into the 'replacement' user's profile folder EXCLUDING the 3 files Ntuser.dat, Ntuser.pol & Ntuser.ini. You will loose some of the desktop 'preference' settings however all your folders and documents should be OK

To see how to use disk 'imaging' to protect your whole system, click "Next>>" in the navigation bar (left)

Using stand-alone RAID mirror NAS units

You can get small high-capacity (2Tb+) RAID mirror NAS units (the 2Tb RAID is advertised as '4Tb', i.e. 2x 2Tb drives). The cost is hardly more than buying the individual drives, so they can be very good value, however they suffer from 2 major problems :-

1) Lack of drive failure indication. Only the 'professional' systems have an audible 'alarm' for single drive failure. Most have a (single) 'indicator' LED which typically doubles as 'software update available' == however loading new software is a fast way to wipe your data, so the 'status' LED just gets ignored. Professional NAS units have one status LED per drive, however no 'commercial' unit has this. So, should you one day 'log-in' to the NAS a discover one of the drives fails, it's typically impossible to discover which one has failed without pulling them out one at a time, which then risks the NAS deciding to 'auto-format' the remaining good drive (see below). Of course when the second drive also fails you will know all about it ... 2) Lack of a reliable 'bad drive swap-out' support i.e. a RAID 'rebuild' function. If you are lucky enough discover a drive has failed (and replace the correct one), you are then faced with the EXTREMELY RISKY process trying to 'rebuild' the mirror from the remaining 'good' drive. Few NAS systems have an easy to use (or even find) 'mirror rebuild' function. Normally, when you set-up a mirror, the NAS will just 'auto-format' both disk drives and wipe everything ... Worse, since most of these units are based Linux core software (and format the drive with something other than NTFS), trying to use the 'good' disk drive on your PC (to manually back-up the contents) won't work either. In sort, a dual disk mirror may give you nothing but double the chance of a disk failure !

Using 2 single drive NAS units

Prices of the 'single drive' NAS have fallen to the point where it makes more sense to install 2 single drive NAS units and 'manually' keep them synchronised.

A 3Tb single drive NAS can be had for about £100. A 6Tb (2x3Tb mirror) NAS from the same vendor costs just under £200.
Plainly a pair of single drive MAS units is a far more reliable approach - it's obvious immediately when one fails PLUS there is no difficulty 'rebuilding' your 'mirror' from the remaining 'good' unit onto a replacement
The trick is to maintain the 2 NAS units in a 'mirror' configuration automatically ... and that's where decent auto-back-up software comes in handy

I now highly recommend using a pair of single drive NAS units (together with Free File Sync) instead of a dual disk Mirror NAS

The pages in this topic are :-

  + Disk imaging - (software)

  + Using scripts - (to preserve your data) == Latest changes (modified 1st Mar 2016 21:35.)

Next page :- Disk imaging - (software)