OT (kinda): defragging with .vobs and huge files on comp.

scottshackrock wrote on 4/6/2005, 12:20 PM
I remember reading soemwhere a while ago that sometimes defragging mixed up large files, such as 1 gig .vobs and/or huge avi's/mpegs, etc. etc.

Is it SAFE to defrag with over 80gig of archived projects/finals on my harddisk that I really want to keep no matter what? haha.

Comments

kentwolf wrote on 4/6/2005, 12:25 PM
It's always safe to defrag whatever, whenever.

BUT...don't pull the power plug in the middle of it. Then, you *will* have trouble. :)
BillyBoy wrote on 4/6/2005, 2:19 PM
Its generally safe to defrag with the idea behind it to restore as many files as possible to "whole" status, meaning all of the file is written one disk sector after another, as opposed to being scattered all over your hard drive. I once did have a power outage during a defrag operation, actually my UPS failed causing exactly what it was suppose to prevent. Wasn't pretty. That's what backups are for. <wink>


UPS = uninteruptible power supply
johnmeyer wrote on 4/6/2005, 3:10 PM
Defragging is safe, but almost always unnecessary. The problem defragging is designed to solve certainly exists: If a file is split into many chunks that are in physically separate parts of the disk, then the disk head must relocate to the next section of the disk to get the next chunk of data. During the time that the head is being repositioned to read the next chunk, no data is read from the disk. In theory, this should make the disk read more slowly.

In the old days, this was true. Back in the days of MFM controllers (we're talking 1980's), the disk would sometimes have to rotate a full revolution or more before the head would be positioned, and if you didn't have the "interleave" set correctly (the stagger between sectors on each concentric track), then additional rotations might be necessary. More importantly, back then, when memory was $150/megabyte, and took an entire board for that much memory (remember the Intel "Above Board"?), the disk controller didn't contain much memory and couldn't cache data. With modern disks, all these problems are ancient history, and it is my belief that defragmentation is, like the appendix in your abdomen, a vestige of previous era that people still believes has some value.

My advice, save the amazing amount of time it takes to defrag your disk, especially with enormous video files.

Don't Defrag!!

It kills me to think of all the time wasted, and for what? I just did a Google search, and I cannot find even one reference to an actual test that shows performance gains after a defrag (except for companies selling defrag software, and even there the claims are extremely vague).
kentwolf wrote on 4/6/2005, 3:28 PM
>>Defragging is...almost always unnecessary.

Well, it's been a few weeks, so I guess we're due... :)
johnmeyer wrote on 4/6/2005, 3:50 PM
Well, it's been a few weeks, so I guess we're due... :)

I guess we did go through this not long ago.
Chienworks wrote on 4/6/2005, 3:55 PM
I've been good! I've only proselytized on this topic once in the past month. ;)

OK, make it twice now ... Defragging is dead. In fact, considering the extra wear and tear on the drive and the fact that it jeopardizes your data while moving it, i would say that defragging is definately more harmful than helpful.
BillyBoy wrote on 4/6/2005, 4:03 PM
If or not defragging is necessary is a debate that's as old as disk drives. As one of two mechanical devices in a typical computer (your floppy drive is the other) a hard drive has moving parts. As a drive's files get more fragemented pieces of files get shuffled around all over the drive. As they get dispersed the drive's read/write heads have to work harder to move sideways and up and down between the platters to find all the parts of the files you're trying to access. This can cause excessive wear on the drive and increases the changes the read/write head will dift out of alignment. Once that happens you may not be able to "read" anything from the drive and you won't be able to access your data.

The flip side is actually doing a defrag also can put lots of wear on the drive especially if the drive is badly fragemented or if you do it daily when not really necessary. A drive that's 70-90% fragemented is not a pretty sight and once that scattered takes forever to defrag.

Over time all drives get more fragemented. Probably the best answer is a compromise. Maybe wait till a drive is 10-15% fragemented, but don't let the task go till it is totally fragemented. Totally ignoring defragging and only considering the speed element and not the wear or danger in letting things go in my opinion is a mistake. Because sooner or later you'll probably defrag or be faced with a drive that's drifted out of alignment. Neither is pretty and both if left undone for too long are a bear to do once you start seeing a drive sputtering.
Chienworks wrote on 4/6/2005, 4:07 PM
If you must defrag, by far the *best* method is to copy all the files to another, nearly empty hard drive. Once you've verified the copies are reasonably intact, do a quick format of the original drive. It's way faster and safer than defragging, and much less wear & tear all around. The only downside is that it requires enough extra drives that you can always keep one relatively empty.
BillyBoy wrote on 4/6/2005, 4:21 PM
Not very practical when you measure your files in hundreds of GB's to have some spare drives to copy everything to. Even if you use one drive and in turn move the contents of one of your 'regular' drives to it in turn then back again that too is going to stress the drive and keep it running for awhile. If the drive you're copying from is fragemented, then you're not avoiding the problem... namely having the drive jump all around in the process of getting all the file fragements in order to 'move' them to the second drive.

What we're really talking about here is BACKUP not defragging. I bet lots of people don't backup on a regular basis or only when they think of it.

I really like my Seagate "backup" drives. They are stackable, (got 3) can be up to 400GB each, have a push button on front that along with the included software only backs up what has changed or is new and not on the backup drive. These little USB 2.0 beauties are only on when backing up, otherwise off so, they have next to no run time except when backing up.
scottshackrock wrote on 4/6/2005, 4:47 PM
hmm, tite. thanks guys. Well I haven't defragged in...almost a year. ha.

so I'd just guess that it's about time...and I do a lot of audio stuff too, and they always say stuff will run more smoothly after a defrag.

either way,i'll just do it overnight and see what happens, hopefully I can trust the school's power. haha

HOLLA!

and thanks a million.
johnmeyer wrote on 4/6/2005, 9:11 PM
and they always say stuff will run more smoothly after a defrag

Does it? Are you sure? Do some scientific measurements before and after. For instance, delete all the prefetch files, re-boot your computer, and then very carefully measure the time it takes each of your favorite applications to load. Then, start the defrag and wait a few hours. When it is finished, delete the prefetch files, re-boot and repeat the measurement. I'll bet good money that you won't be able to measure the difference. By contrast, it is very easy to measure the amount of time (hours) it takes to defrag a very full 200 Gbyte hard drive.

Try finding any measurement statistics on the web that are not tied to some defrag vendor's site. They don't exist. Yet eveyone still believes that defrag buys them something.

Here's another test, much more relevant to this forum. Find a project that can be rendered in less than half an hour. Go ahead and render it. Then, defrag the disk, reboot, and render again. What was the difference in time? Since it takes hours to defrag, you darn well better see some impressive improvements. I'll be you can't measure it at all.

Finally, what about capture? This forum gets lots of posts about capture problems, especially dropped frames. Most such threads include a recommendation to to defrag the hard drive. I've probably even made such a recommendation. However, I am certain that I have never seen anyone write that they had just defragged their hard drive, and all their capture problems went away.

If you want to defrag, then frag away, but make sure you are doing so based on scientific testing information and not on outdated assumptions that were true in a bygone era, but are no longer true.