>>>>> "Doug" == Doug Ledford <dledford@xxxxxxxxxx> writes: Doug> On Fri, 2007-10-19 at 12:38 -0400, John Stoffel wrote: >> 1, 1.0, 1.1, 1.2 >> >> Use the new version-1 format superblock. This has few restrictions. >> The different sub-versions store the superblock at different locations >> on the device, either at the end (for 1.0), at the start (for 1.1) or >> 4K from the start (for 1.2). >> >> >> It looks to me that the 1.1, combined with the 1.0 should be what we >> use, with the 1.2 format nuked. Maybe call it 1.3? *grin* Doug> You're somewhat misreading the man page. The man page is somewhat misleading then. It's not clear from reading it that the version 1 RAID superblock can be in one of three different positions in the volume. Doug> You *can't* combine 1.0 with 1.1. All of the above options: 1, Doug> 1.0, 1.1, 1.2; specifically mean to use a version 1 superblock. Doug> 1.0 means use a version 1 superblock at the end of the disk. Doug> 1.1 means version 1 superblock at beginning of disk. `1.2 means Doug> version 1 at 4k offset from beginning of the disk. There really Doug> is no actual version 1.1, or 1.2, the .0, .1, and .2 part of the Doug> version *only* means where to put the version 1 superblock on Doug> the disk. If you just say version 1, then it goes to the Doug> default location for version 1 superblocks, and last I checked Doug> that was the end of disk (aka, 1.0). So why not get rid of (deprecate) the version 1.0 and version 1.2 blocks, and only support the 1.1 version? Why do we have three different positions for storing the superblock? And if putting the superblock at the end is problematic, why is it the default? Shouldn't version 1.1 be the default? Or, alternatively, update the code so that we support RAID superblocks at BOTH the beginning and end 4k of the disk, for maximum redundancy. I guess I need to go and read the code to figure out the placement of 0.90 and 1.0 blocks to see how they are different. It's just not clear to me why we have such a muddle of 1.x formats to choose from and what the advantages and tradeoffs are between them. John - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
