Sunday, December 27, 2009

Thoughts On Various Imaging Solutions

ShadowProtect, Windows/SBS Backup, Backup Assist, Acronis TrueImage, R-Drive Image, Macrium Reflect, Image for Windows, DriveImage XML and a number of similar products exist and will all provide faster recovery times on the same hardware than a file-based backup and server rebuild could possibly enable. Some of these products also enable Hardware Independent Restore (HIR) as well, enabling you to restore an Open License/Open Business/FPP licensed (but not an OEM) Server or Desktop OS from one piece of hardware to another - ShadowProtect and Acronis being the most common two for this, however Backup Assist can also manage HIR quite nicely.

Now, there's 2 main ways that these products handle Full + Incremental backups - most of them create a single full image and then create additional incrementals, each building upon the full + previous incremental (or they handle full + isolated differentials), however Windows/SBS Backup (and therefore Backup Assist as it uses the Windows backup engine) creates a full backup that is the current/latest backup and negative incrementals (or decrementals) which are what was changed to go back in time. Basically the two methods are diametrically opposed in their thinking - most products give you a full that requires all incrementals (or the latest differential) to get you back to "latest" whereas Win/SBS backup and Backup Assist only require restoration of the last full backup to get you where you want to be.

Now, this difference in methodologies doesn't mean one is more right nor more wrong - it is just a difference in approach.

If you're looking into image backups as a (or part of a) backup strategy, I'd strongly recommend having a separate spindle in the server itself and then having the removable hard drives located in whoever's computer is tasked with taking the backups offsite - this works for all products that are *not* based on the Windows Backup engine as it requires Volume Shadow Copy snapshots to be present, and these are not copied across from the internal HDD to a removable HDD using RoboCopy. This is a much, much better option than having users add/remove hardware at the server directly - it is never really a good move to have users physically touching the server if you can possibly help it as their grubby, greasy hands, swine flu sneezing and dandruff will often make a server feel uncomfortable. OK, maybe not quite like that, but you know what I mean... :) Have the snapshots on the extra spindle then copied using some form of magic (robocopy, richcopy, goodsync, etc) across the network to these removable HDD units overnight and they will appear ready and willing for removal when the users rock up to work, bleary-eyed from a hard night on the turps.

If you're looking at replicating this same backup strategy to a cloud-based service (including to a large system on your own site) then you should look at using an Incrementals Forever strategy as this will reduce the size of data streamed across the Internet. Using Win/SBS Backup and/or Backup Assist won't work well in this scenario because of its "full = latest" strategy, unfortunately. ShadowProtect (and likely Acronis) will work rather well. One good thing with ShadowProtect (and I assume Acronis have this feature, too) is a handy little util that will look at an incremental and the whole tree back to the full backup and verify it. Another good thing is the ability to roll up daily, weekly, monthly, wheneverly incrementals into a big single incremental to save the need to keep multiple incrementals and need to restore them all, however there is no *need* to do this as the latest incremental will cause all prior backups right back to the full to be used for the restore.

So, having a client use, say, hourly incrementals between 8AM and 6PM weekdays that are based off a single full backup, then a midnightly incremental, and rolled up on Sunday to a single incremental will keep the file manageability down to a sane level, will mean you can push the daily backups up to an online bit bucket using rsync, and if this system is on your site (or a hosted server somewhere) then you can schedule image verifications daily and be notified if there are any issues as and when they occur.

All up, Image backups have many ways they can be used and offer a good form of onsite/offsite/online backup in almost a single process.

I'd *still* perform file backups onto a different media (such as DVD-RAM or Amazon S3) of what I call the client's "bankrupt data" - the data that if they cannot get back almost immediately, can send them into bankruptcy - their accounting data and quite possibly a LOB application's data.

The Outspoken Wookie

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