Are partitions discrete areas?

[jaydub868]

Are partitions on a hard drive discrete areas? That is to say, if you have a single platter hardrive with four parititions, is the data in any one partition physically separated from data on other partitions? Or is data for any one partition spread out all over the drive but somehow flagged as "belonging" to a particular partition?

 

[tlmck]

See if this answers your question. http://en.wikipedia.org/wiki/Partition_(computing)

 

[bobbknight]

Simply, Yes.

 

[apache_lives]

Are partitions on a hard drive discrete areas? That is to say, if you have a single platter hardrive with four parititions, is the data in any one partition physically separated from data on other partitions? Or is data for any one partition spread out all over the drive but somehow flagged as "belonging" to a particular partition?

put it this way, you loose a hdd, you loose everything including all the patitons, and no, patitions dont seperate between platters and what not.

 

[tmike]

they're not segregated per se, but they are effectively contiguous media regions. like a phone book, the 'a's are segregated from the 'b's but only because of perception - its really just one big long book. This assumes that you consider a cylinder to be a logically contiguous area, even though by definition a cylinder is not physically contiguous space because it spans platters.

Altho, there is no reason that a drive must be implemented this way - after all, technically the drive could use a spiral notebook with bits written in crayon as long as it looked right from the outside.

Evidence of this being the actual implementation used can be seen by noting the large performance difference between partitions stored toward the outside edge of the platters and those on the inner cylinders. If you were to find a drive that did not exhibit this behavior, then that would imply some other implementation. If for some reason consistent performance across the drive were paramount, then an alternative implementation (such as one that involved distributing the data in blocks across the entire drive, or perhaps even just aggregating by tracks instead of by cylinders) could be useful. I have never seen such a drive, most likely because aggregation of cylinders means that the heads don't have to be repositioned as often (imagine a partition that occupied a single cylinder's amount of space: with no head movement at all, the entire partition is accessible); the tradeoff (for a drive with a constant-speed spindle) is that some of your partitions are relatively fast and some are relatively slow.

 

[favoritetort]

are logical volumes?

 

[tmike]

are logical volumes?

logical volumes are comprised of one or more areas (Physical Extents) that are each contiguous regions resembling partitions. the individual regions can be created in any free space that is on spindles that are in the same Volume Group (altho IIRC, windows doesn't use Volume Groups, so all dynamic disks are effectively one Volume Group - but normally that is not the case.) The LV's size can be increased at any time by adding new regions, so an LV can consist of areas that are scattered over a spindle or over multiple spindles. The individual chunks are, however, partition-like in size (i.e., large - typically GB or TB in size). As with partitions, careful planning (or manual redistribution of the chunks to multiple spindles or controllers) can dramatically affect performance (altho - again IIRC - windows doesn't provide tools to move physical extents altho other implementations of LV do).