claudio@ethz.UUCP (Claudio Nieder) (10/22/86)
[ ]
Matt Dillon showed us the advantage of trackbuffers for speed
improvment, but they could also help to increase safety.
C-A states an advantage of the used filesystem is its safety.
The loss of one block will damage no more than one file. This
is true, but I never losed only one block. Usually it happens when I'm
in a hurry. I pull out a disk while the LED is still on indicating
the drive is still writing. What happens now:
1. I pull out the disk during a write.
2. AmigaDos request me to reinsert disk foo:.
3. I put foo: into the drive.
4. AmigaDos tries to read, and then puts up a requestor
foo: has read/write error.
And so I lose 11 blocks, which can cause the damage of upto 11 files !
Following could happen if several trackbuffers are available and if
AmigaDos and trackdisk.device cooperate:
1. I pull out the disk during a write.
2. The currently used trackbuffer will be marked as locked.
3. AmigaDos requests me to reinsert the disk foo:.
4. I put foo: into the drive.
5. AmigaDos checks that it is not the wrong disk.
6. The locked trackbuffer is written to the disk.
7. If the write was successful, the trackbuffer is freed.
No loss of data at all, a really safe filesystem !!!
--
claudio
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Mail: Claudio Nieder, Kanalweg 1, CH-8610 Uster, Switzerland.
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