At 8:11 PM -0400 3/20/2009, Charles Davis wrote: > > I've always assumed partitions were being treated like a separate > > volume, and was being re-mapped. > >That's the way I'd like it to be, which means that the 'Bad Blocks' >routines probably only work when Zeroing the complete Hard Disk.
No. The HD has no clue as to any logical set-up created on it by the driver / file system / OS in your computer. IOW, the HD is simply a stream of data blocks, and the controller a server thereof. All the partitions and such are logical constructs created in your computer only. Operations you do - move files around, zero things, etc, are meaningless to the HD's controller. It just sees the individual read and write commands sent to it by the driver. The HD's controller is smart wrt individual data blocks and the physical geometry of the drive *only*. In general (and *highly* simplified),... - A chunk of disk space is "reserved" for block replacements. - The driver issues logical read or write commands to the controller. The controller buffers things, screws around, etc, and eventually performs physical read or write operations. - The results of a physical read or write operation is checked against some ECC type codes *by the controller*. If the i/o operation, a test is initiated: the block is read and written repeatedly to see if the correct data can be pulled off of it. If the block finally reads ok, life continues. If the block continues to fail then it is "mapped out", a replacment block is chosen, and a best-guess of the data is written to it. The trick is... that this all occurs between the controller and the HD mechanism. The computer has no idea it happened unless it asks for status. (that's where the SMART reporting stuff comes in). Iffa it no ask, it stays clueless. Now... We often recommend zero'ing a HD in order to handle "stale" blocks. The controllers bad block replacement is always active --- but it doesn't see a bad block until it's commanded to actually touch (read or write) that block! Zero'ing touches every block, thus forcing bad block mapping, hopefully before you put critical data there. HTH, - Dan. -- - Psychoceramic Emeritus; South Jersey, USA, Earth --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed Low End Mac's G3-5 List, a group for those using G3, G4, and G5 desktop Macs - with a particular focus on Power Macs. The list FAQ is at http://lowendmac.com/lists/g-list.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/g3-5-list?hl=en Low End Mac RSS feed at feed://lowendmac.com/feed.xml -~----------~----~----~----~------~----~------~--~---
