>>>>> "Peter" == Peter Grandi <pg@xxxxxxxxxxxxxxxxxxxx> writes: Peter> There are some obvious wins to addressing in 4KiB sectors, the Peter> most important of which is the avoidance of RMW as a possibility. There are also drives where you can disable RMW explicitly. I.e. the drive appears as 512e but will reject any misaligned non-multiple of 4K. The downside to 4Kn is that it breaks applications using direct I/O that assume that the sector size is 512 bytes. Which essentially means all of them. Solaris opted to do RMW in software to overcome that issue. Whereas we are trying to get application writers to fix their code... Peter> But there is another important short term win, as older storage Peter> protols and formats relate maximum disk or partition or filetree Peter> capacity to maximum number of sectors addressable, which is often Peter> fixed at below 2^32 or 2^31, so addresses in units of 4KiB Peter> sectors allow 8 times more capacity than 512B ones. Yep. Although in Linux we use 512-byte sectors throughout the I/O stack regardless of the device's logical block size. -- Martin K. Petersen Oracle Linux Engineering -- 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
