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| Thread ID: 60853 | 2005-08-15 10:14:00 | Hard Drive Data Placement | Poppa John (284) | Press F1 |
| Post ID | Timestamp | Content | User | ||
| 381472 | 2005-08-15 10:14:00 | When looking at the HD to defrag, the data appears scattered all over the place. What determines, when something is saved to the HD, where anything is placed. for instance, the front of the bar is full of blue. The middle is almost empty. Yet things are placed at the end of the defrag bar. Why? PJ | Poppa John (284) | ||
| 381473 | 2005-08-15 10:18:00 | defrag will often move data that rarly ever gets used to the back of the drive. this leaves the faster area of the drive free for commanly used programs to occupy. | tweak'e (69) | ||
| 381474 | 2005-08-15 10:29:00 | OK I hear what you are saying. But. I am watching Maryann's computer do a defrag & everything red & blue is moving across to the Left side. The green will not move, I know. Incidentally. How does an HD or a CD fill up, from the middle out, or the "out" into the middle? PJ |
Poppa John (284) | ||
| 381475 | 2005-08-15 10:46:00 | The green if youre talking about Ms's defragger means they're unmovable files. Thats why they dont move. Its just the way MS defragmenter works. The red are fragmented and blue contiguous file. |
Speedy Gonzales (78) | ||
| 381476 | 2005-08-16 02:08:00 | Defrag has several purposes: 1. keep elements that are part of the same file together, of course, 2. keep some groups of files together (those listed in the prefetch list mainly), 3. keep all files as close to each other as possible so that a. the heads won't need to chase all over the disk for them b. large chunks of free diskspace are available for large files. The limitations are: files that are in use can't be moved (those are the files in green, mostly OS files, but can be other apps if they are running while defrag is started, hence better results if defragging in safe mode), compressed files need to be decompressed before they can be defragged (if defrag can't decompress them-for example iso files- OR if there isn't a large enough portion free diskspace in the immediate vicinity of the compressed file to hold the uncompressed version, defrag will skip that file), defrag will then find the largest fragment of one fragmented uncompressed file and try to move other fragments of the file so that they will be whole. If the free space runs out around that original fragment then defragmentation of that file will stop even if more fragments are present. Best practices: if you plan to create a large file, especially a compressed one like an ISO or a movie, defrag that partition first. When defragmenting the partition with the paging file on it, move the paging file first, as this will free up to 2 GB depending on your settings. Moving the paging file requires a reboot so boot into safe mode and run defrag from a command prompt (fewer apps running, faster defrag). Hope this is more helpful than confusing, A. |
antonia1 (7850) | ||
| 381477 | 2005-08-16 02:25:00 | The OS file system decides where things are put in the first place . There are various algorithms, and it all becomes a bit complicated . I've only used a couple of OSs which allowed the user to specify exactly where on a disk to create a file --- I even used it a few times (with the command CREATE /ALLOCATE=5000 . /START=23445 data . dat) . I believe Windows XP does a fair amount of file moving as part of its ongoing optimisation . Their aim is to get frequently used files (mostly applications) close together to minimize head movement . Defrag doesn't seem to care much what sorts of files are, and where XP thinks they should go . It has to be a bit careful about moving files which are in use . If the OS has decided where something is, it's not helpful to move the thing . (You've probably noticed the OS's reaction when you've put something away in the kitchen, PJ; or your own reaction when MJ has tidied your workspace for you) . Defrag is just trying to reduce or eliminate fragmentation . Defrag probably works against the XP optimisation . ;) These days, fragmentation is probably not as much of a problem as people seem to believe . Very clever disk software can arrange accesses so that a bit of scattering doesn't cause any speed loss . |
Graham L (2) | ||
| 381478 | 2005-08-16 07:04:00 | Most interesting, thanks to all. How about the other question. Does a disc fill from the center out, or the outer to the centre.?? PJ |
Poppa John (284) | ||
| 381479 | 2005-08-16 07:44:00 | How about the other question. Does a disc fill from the center out, or the outer to the centre.?? PJ HDD are outer to inner, CDs are inner to outer. |
godfather (25) | ||
| 381480 | 2005-08-16 08:35:00 | HDD are outer to inner, CDs are inner to outer. Thanks for that. How odd !!!!! PJ |
Poppa John (284) | ||
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