[Ukfreebsd] File System Ext2 On DVD+RW

Frank Mitchell mitchell at wyatt672earp.force9.co.uk
Sat Dec 20 18:49:45 GMT 2008


Recently I noticed Sun Solaris used CDs with a UFS File System. So I decided 
to try UFS and Ext2 on Optical Disks. It should work on CD-RW, but I had 
spare DVD+RW disks, so I decided to get more ambitious.

Note that DVDs use 2048-byte Sectors like CDs, but they're handled in 
Error-Correcting Blocks of 16. You can't expect DVD-RW to work, because 
DVD-RW only writes complete ECC Blocks. But DVD+RW (like DVD-RAM) can
update individual Sectors.

FreeBSD UFS1 wouldn't work this way. The FreeBSD Handbook gives instructions  
for DVD-RAM, and obviously DVD-RAM has a different layout. But OpenSUSE Linux 
seems okay with Ext2 on DVD+RW. I copied a large Subtree and checked the 
result using diff -qr.

Does anybody have thoughts about this idea? Like: Any disadvantages which 
haven't occurred to me? Obviously if you're recording Personal Information on 
Removable Media it might be preferable to use a format which isn't readable 
under  Windows.

Faictz Ce Que Vouldras: Frank Mitchell

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