RE: ext3 file system

From: jshankar
Date: Wed Dec 17 2003 - 18:27:47 EST


Hello,

Please provide some more insight.

Suppose a filesystem issues a write command to the disk with around 10 4K
Blocks to be written. SCSI device point of view i don't get what is the
parallel I/O.
It has only 1 write command. If some other sends a write request it needs to
be queued. But the next question arises how the write data would be handled.
Does it mean the SCSI does not give a response for the block of data written.
In otherwords does it mean that the response would be given after all the
block of data is written for a single write request.

Thanks
Jay




>===== Original Message From Mike Fedyk <mfedyk@xxxxxxxxxxxxx> =====
>On Wed, Dec 17, 2003 at 05:25:49PM -0500, Richard B. Johnson wrote:
>> to the physical media. There are special file-systems (journaling)
>> that guarantee that something, enough to recover the data, is
>> written at periodic intervals.
>
>Most journaling filesystems make guarantees on the filesystem meta-data, but
>not on the data. Some like ext3, and reiserfs (with suse's journaling
>patch) can journal the data, or order things so that the data is written
>before any pointers (ie meta-data) make it to the disk so it will be harder
>to loose data.
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