On 2011. 01. 17., Monday 15:15:13 Greg Freemyer wrote:
On Mon, Jan 17, 2011 at 3:42 AM,
wrote: On 2011. 01. 17., Monday 05:43:29 Andrew Joakimsen wrote:
I've installed a new RAID array in my home server and the disks are using 4KB sectors instead of the traditional 512 byte sectors.
How do I properly align the partitions to this disk? YaST partitioner shows "cylinders" and I can not come up with a formula to convert cylinders to sectors. My understanding is since 8 x 512 = 4096 (4kb) all I need to do is ensure that my partitions are aligned to multiples of 8 sectors.
Unfortunately, it is not that trivial as aligning partition boundaries to multiples of 8. See this article (and comments): http://lwn.net/Articles/377895/
That article is concerned with 4KB physical sector drives with 4KB logical sector addressing. That is highly uncommon.
Please check again. A quote: "One simply cannot run XP on a device which has been properly partitioned for 4K physical sector sizes. To cope with that, drive manufacturers have introduced an even worse hack: shifting all 512-byte logical sectors forward by one, so that logical sector 64 lands at the beginning of a physical sector. So any partitioning tool which wants to lay things out properly must know where the origin of the device actually is - and not all devices are entirely forthcoming with that information. " This is the main reason I referred the original poster to the article: 512-byte logical sectors may be shifted by one.
Most drives of concern have 4KB physical and 512 byte logical sectors.
For them, alignment is the only issue.
hdparm can show you your logical / physical sector size and I think both are in /sys/block/sda/queue/*. You can use a liveCD to look at that I assume prior to installing.
Greg
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