On 1/2/2014 10:31 AM, Phillip Susi wrote: > On 1/2/2014 10:41 AM, Stan Hoeppner wrote: >> First, there is no such thing as a 4K sector in Linux. Sectors are >> 512 bytes. Filesystem blocks and memory pages are 4K. > > Of course there is. Disks with 4k sectors are becoming more and more > popular. Please read: https://en.wikipedia.org/wiki/Advanced_Format There are no native 4K sector drives on the market. Linux does not support a native 4K sector size, only 512 bytes, unless this has changed in recent kernels and I'm simply not aware of it yet. > CD-ROM type drives have always used 2k sectors. Also This is not relevant to this discussion. > filesystem blocks and memory pages aren't necessarily 4K, though that > is the most common size. Yes, they are necessarily 4K in Linux. Linux only supports page sized BIO for consistency across the memory manager and IO subsystems. Most architectures which Linux currently supports have hardware page sizes greater than 4K, for instance IA64 supports 4k/8k/16k, even a 4GB page size. But it was decided long ago to stick with 4K for a number of reasons, one of these is stated above. For background on this Google is your friend. >> read the data chunk of the stripe in which the 4 sectors of the >> 4KB > > You mean 8 sectors, assuming you're still talking about 512 byte sectors. Yes, 8 sectors, thanks for catching my brain to finger err. The ONLY thing to talk about is 512 byte sectors because this is the only sector size Linux supports. -- Stan -- 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
