Re: Granularity of disk I/O

1999-11-03 Thread Luoqi Chen
> :Thanks. It seems to me that for a filesystem, a block (or a fragment) is > :the unit of I/O. Even if a single byte is modified, an entire block > :probably consisting of multiple sectors must be written back to the disk. > :As you said, there is no differnce whether we write this block one sec

Re: Granularity of disk I/O

1999-11-03 Thread Matthew Dillon
:Thanks. It seems to me that for a filesystem, a block (or a fragment) is :the unit of I/O. Even if a single byte is modified, an entire block :probably consisting of multiple sectors must be written back to the disk. :As you said, there is no differnce whether we write this block one sector :at

Re: Granularity of disk I/O

1999-11-03 Thread Zhihui Zhang
> From the system's point of view, there is no difference in reliability > between doing a single sector transfer and a multi-sector transfer > except for the size of the retry. Since retries do not occur very often > nobody really cares how big the retry is. Since there is a hu

Re: Granularity of disk I/O

1999-11-03 Thread Matthew Dillon
: :Thanks for your reply. I know that directory entries are physically :prevented from crossing device block boundaries in order to ensure atomic :update. If I write a directory file with a buffer (using some kind of :multi-sector transfer) and do not know which sector within the buffer :fails, w

Re: Granularity of disk I/O

1999-11-03 Thread Zhihui Zhang
On Tue, 2 Nov 1999, Greg Lehey wrote: > On Tuesday, 2 November 1999 at 17:10:41 -0500, Zhihui Zhang wrote: > > > > 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. &g

Re: Granularity of disk I/O

1999-11-02 Thread Greg Lehey
On Tuesday, 2 November 1999 at 17:10:41 -0500, Zhihui Zhang wrote: > > 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 some

Granularity of disk I/O

1999-11-02 Thread Zhihui Zhang
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

Re: Granularity of disk I/O

1999-01-02 Thread Peter Jeremy
On Wed, 3 Nov 1999 11:37:42 -0800 (PST), Matthew Dillon <[EMAIL PROTECTED]> wrote: > The directory blocking is there for a different reason. Atomicy does not > have much to do with it though perhaps it did at some point in the past. Hmmm... /usr/include/ufs/ufs/dir.h states: * A directory con