On Tue, Mar 17, 2009 at 3:25 AM, jdd wrote:

David Haller a écrit :

...

these as such. Show the complete 'fdisk -l' output (via PM) ...

shows exacltly the same thing I posted in my first post.

This discussion is very interesting, even if it go much more complicated I thought initially.

I'm the "Partition Rescue" LDP HOWTO author and become recently the LDP coordinator. I was sometime asked to include my HOWTO in the Partition HOWTO and, as the Partition HOWTO author didn't want to continue with it I decided to take the HOWTO authorship.

But the present HOWTO: http://tldp.org/HOWTO/Partition/index.html looks to me much too old, given all the new partitionning tools and disk usage we have now, so I began rewriting all this. It's *not* yet done. Drafts are here http://wiki.tldp.org/Partitions-and-mass-storage-HOWTO

Some years ago, I made a course and for my students sake made use of loop mounted files as partition and file system testbed. I may use this also now for examples, but it's also easy to use usb keys, now so cheap user can (eventually) destroy one without real problem :-)

But I don't want to write on a subject before understanding it fully. Thas is why I did this post.

among others, a curious thing is that I perfectly remember that at the moment LBA was introduced, it was presented as a way to show CHS with fake numbers.

I have yet to control this, but ATM most Bioses showed different CHS layout with LBA activated or not, but never shown direct sector numbers. It's only when Linux come than this direct adressing was used and never in partitionning tools.

When fdisk advertise the 1024 cylinder barrier, I don't have found PC with this problem for more than 10 years now.

My goal is to try making clear the bare minimum necessary to make actual partitionning on fixed and also external disks.

as of LBA, this seems pretty cool: http://www.dewassoc.com/kbase/hard_drives/lba.htm

thanks jdd

On Tue, Mar 17, 2009 at 3:25 AM, jdd wrote: <snip>

This discussion is very interesting, even if it go much more complicated I thought initially.

I'm the "Partition Rescue" LDP HOWTO author and become recently the LDP coordinator. I was sometime asked to include my HOWTO in the Partition HOWTO and, as the Partition HOWTO author didn't want to continue with it I decided to take the HOWTO authorship.

But the present HOWTO: http://tldp.org/HOWTO/Partition/index.html looks to me much too old, given all the new partitionning tools and disk usage we have now, so I began rewriting all this. It's *not* yet done. Drafts are here http://wiki.tldp.org/Partitions-and-mass-storage-HOWTO

Some years ago, I made a course and for my students sake made use of loop mounted files as partition and file system testbed. I may use this also now for examples, but it's also easy to use usb keys, now so cheap user can (eventually) destroy one without real problem :-)

But I don't want to write on a subject before understanding it fully. Thas is why I did this post.

among others, a curious thing is that I perfectly remember that at the moment LBA was introduced, it was presented as a way to show CHS with fake numbers.

I have yet to control this, but ATM most Bioses showed different CHS layout with LBA activated or not, but never shown direct sector numbers. It's only when Linux come than this direct adressing was used and never in partitionning tools.

When fdisk advertise the 1024 cylinder barrier, I don't have found PC with this problem for more than 10 years now.

My goal is to try making clear the bare minimum necessary to make actual partitionning on fixed and also external disks.

as of LBA, this seems pretty cool: http://www.dewassoc.com/kbase/hard_drives/lba.htm

thanks jdd

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JDD, I think it is great you are working on that howto. I consider myself very knowledgeable about partitioning and I've learned a few things about new concerns in just the last month or two. Herbert's comment about SDD's needing special partition alignment in particular was a new concept for me. And the 4k sector drive issue was new to me last month. Getting that info into a core HowTo like the LDP is great to see in such a timely manner. I suspect you've bitten off way more than you expected, but it is a very worthwhile project. Anyway I've scanned the draft and I have a couple hopefully constructive comments: 1) Under software tools, I would like to see gpart listed and then a link to later in the doc where you already explain how it is used. 2) As I assume you already realize, you need to add a section on partition alignment. As noted before, in the days when CHS represented real disk geometry, partitions were aligned with the start of a track. Linux still defaults to that for the first partition for no real reason as far as I know. (Herbert implied bios'es and boot code may still need that?) Vista has changed the default to use 1 MiB offset into the disk for the first partition and ignores CHS geometry altogether AIUI. New devices with atomic write units larger than 512 bytes have come to market or soon will and need to be addressed. They require special alignment. Apparently some new devices are trying to use CHS to convey their alignment needs to the OS / partitioning tools. Others may not be. 2.1) Just yesterday I saw a post that some SSDs monitor the partition table contents and realign themselves internally to make the alignment work. (That is just plain crazy to me, but it is what it is.) Worthy of a comment in the HowTo assuming it is true. 3) The HowTo talks in detail about the IBM PC partition table concept, but does not even mention GPT or any other partitioning scheme (that I noticed). GPT is now the default partition table format used on Macs, and Microsoft Vista supports it for data disks. (ie. In general, not supported for booting Vista from. Possibly one can make it work?) The old IBM PC format maxes out at 2TB I believe, so GPT or something else is coming. I believe GPT is the recommended Linux Partition table for drives (logical or physical) that exceed 2TB. I think *some* PC bios'es already support booting from GPT partitioned drives. Obviously the Mac line does. (I don't think fdisk supports GPTs, so another partitioning tool would have to be used.) 4) No reference to /proc/partitions. (Is there an equivalent in /sys ?) 5) Is a section about future ideas appropriate? In particular I personally think all of the Linux partitioning tools need a conceptual update to get away from CHS being treated as fundamental to the layout of disk drives. Even Microsoft has dropped that concept. 5.1) In the linux world, how do big conceptual changes like that come about. I'm familiar with LKML, and I assume there are individual mailing lists for various partitioning tools, but if the Linux community wanted to follow Microsoft's lead and start using 1 MiB as the default starting point for new sectors, how would that decision be reached and how would it get propagated out to the various tool developers? 6) This thread http://markmail.org/message/tn5lfbf36dy6h2ox about 4K sectors is worth at least you reading and possibly a good reference to add to your doc. Greg -- Greg Freemyer Head of EDD Tape Extraction and Processing team Litigation Triage Solutions Specialist http://www.linkedin.com/in/gregfreemyer First 99 Days Litigation White Paper - http://www.norcrossgroup.com/forms/whitepapers/99%20Days%20whitepaper.pdf The Norcross Group The Intersection of Evidence & Technology http://www.norcrossgroup.com -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org