Effect Of Defrag

[Joebocop]

In the forever-incremental model, if I defrag my HDD one day, will an enormous backup job be invoked that night, seeing as blocks have been moved all over the drive?

Thank you.

[Dima P.]

Hello,

seeing as blocks have been moved all over the drive

Due the nature of change block tracking yes - such incremental backup size will be close to the size of the full backup, but I believe this happens rarely, right?

[ninjaburn81]

...if ever, at least manually?

With Windows 7 and (done much better in) 8, defragging is done automatically. And if you are using a SSD, it is never required. But still, it's an interesting question.

I know what I'm testing Monday! (Left my USB drive at work!)

[Dima P.]

Adam,
Keep it up! I hope you’ll share the results

[ninjaburn81]

Did tests on two PCs, both running SATA spinning drives, plus I looked at when the disk defrag runs and compared the incremental that occurs before vs after the incremental that happens after.

Average increase of data read increases is 45%, average increase in restore size is 50%, compared to the previous INCREMENTAL. That is key because that is what the normal backups will be. Total time difference was negligible however.

Final Conclusions:
1) Disk Defrag runs automatically anyway on Win7 and later, so for the most part your system will almost never suffer from serious defrag.
2) The effect of defrag is negligable on the VEB backup time.
3) Backup size does increase, but since it is an incremental, this will only noticeably affect backups running on systems that have large amounts of data changing regularly, such as a file server or a system being used to batch change files (media developers).

[ninjaburn81]

P.S. Forgive the horrendous grammar, it was a crazy day and I kept jumping in and out of writing that post...ugh!

[Dima P.]

Adam,
Awesome! The results are even better than I expected, so kudos for checking – QA will be happy to hear.

[ninjaburn81]

You're welcome!

[TommyB]

I always turn defrag off on all my Windows PCs... last time I defragmented a drive was around 1994 - at that times, with FAT file systems it often made quite a difference, especially with small drives and flat file database tables like dBase-III... but with NTFS I never saw a big effect, so I decided to take the additional wear away from the hard drives.

[Dima P.]

Thomas,Agree.

For the past 5 years I’ve started defrag manually only once. I aslo checked the default auto defrag settings on my PC ( only after Adam’s post ) - it is set to weekly, and yes SSD is excluded by default.

By the way if somebody is looking guidance on how to enable auto defrag (or at least check it is enabled) – here it goes: Schedule Disk Defragmenter to run regularly