Date: Tue, 2 Nov 1999 17:10:41 -0500 (EST) From: Zhihui Zhang <zzhang@cs.binghamton.edu> To: freebsd-hackers@freebsd.org Subject: Granularity of disk I/O Message-ID: <Pine.GSO.3.96.991102165830.16585A-100000@sol.cs.binghamton.edu>
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It is said that the granularity of disk I/O is a sector. I read a little bit of the source code isa/wd.c, which I think is the driver of IDE disks. I find out that the disk can perform multi-block I/O sometimes. Does this mean the granularity of disk I/O can be multi-sector? If the disk can perform DMA, what is the usual DMA size? Is the granularity the DMA size in this case? If a buffer cache is larger than one sector, it should be split into sectors before I/O. If an I/O on a buffer fails, can we tell which sector within that buffer fails? I am confused with these things and it is probably that my questions are confusing too. Any help or hints are appreciated. -Zhihui To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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