Barriers and journaling filesystems
Posted May 25, 2008 2:47 UTC (Sun) by giraffedata
In reply to: Barriers and journaling filesystems
Parent article: Barriers and journaling filesystems
but on modern disks you really don't know where the borders of a track are. it's really just
an array of blocks
I don't know what "but" refers to here; I made a statement about "if I were a disk drive," and the disk drive definitely knows where the borders of the tracks are. And though I have no actual evidence of it, I would be very surprised if the disk drive did not use that knowledge to optimize performance.
The idea suggested in the article that ext3 tends to get ordered writes (to the platters) because it usually does journal updates in logical block number order seems to assume that the disk drive does writes from cache to platter in logical block number order. I can't believe that it would do that, even usually, because it would be so much slower than optimum.
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