Theodore Ts'o wrote: > I attended the IDEMA (International Disk Drive Equipment and Materials > Association) conference today to give a talk about Linux, and during one > of the breaks I got buttonholed by someone who asked me if I could help > make sure Linux would be able to deal with the upcoming HDD sector size > move from 512 to 4096. Just coincidentally, I ran across the following > article from Slashdot, "Which Operating System Is Best For solid-state > disks": > > http://www.computerworld.com/action/article.do?command=viewArticleBasic&taxonomyName=Storage&articleId=9123140&taxonomyId=19&pageNumber=1 > > Quoting from that article, Justin Sykes from Micron Technologies stated: > > "NAND [flash memory] fundamentally has native 4K block > sizes. Anything that's not aligned to a 4K block creates extra > challenges," Sykes said. "There ends up being background > operations to garbage-collect that empty space [in larger file > blocks] that isn't fully utilized. And, so that activity is > chewing up your bandwidth in the background, and it adds extra > wear to the NAND [flash memory]." > This, of course, is complete bunk -- most NAND flash has much larger erase blocks than 4K. > I fully expect that perhaps someone from San Disk or Intel will pop up > and say that "this is just Micron's SSD's suck; *our* SSD's won't have > this problem". Perhaps; but HDD's won't be going away any time soon[1], > and they will be moving to a 4k block size in the next few years. > > So what's the problem? The main problem seems to be that by default, > we are using partition tables that cause the partitions to be not > aligned on 4k boudaries, because of the default hdd geometry used by our > partition tools and returned by the HDIO_GETGEO ioctl: This is certainly a problem. This one is bad for performance in general and is based on completely outdated DOS conventions. It should have been fixed ages ago by aligning to power-of-two boundaries, of at least 64K I would say. I believe Vista uses 1 MB boundaries. A much bigger potential problem can occur if there are assumptions about the atomicity of writes, plus the inevitable BIOS/boot loader problems. EFI could have done something smart by making the hardware sector size less visible, but did the opposite. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf. -- To unsubscribe from this list: send the line "unsubscribe util-linux-ng" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
