Messages in this thread | | | Date | Mon, 21 Apr 2003 13:03:41 +0200 | From | Stephan von Krawczynski <> | Subject | Re: Are linux-fs's drive-fault-tolerant by concept? |
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On Mon, 21 Apr 2003 10:35:21 +0100 (BST) John Bradford <john@grabjohn.com> wrote:
> > > > What is so bad about the simple way: the one who wants to write > > > > (e.g. fs) and knows _where_ to write simply uses another newly > > > > allocated block and dumps the old one on a blacklist. The blacklist > > > > only for being able to count them (or get the sector-numbers) in > > > > case you are interested. If you weren't you might as well mark them > > > > allocated and that's it (which I would presume a _bad_ idea). If > > > > there are no free blocks left, well, then the medium is full. And > > > > that is just about the only cause for a write error then (if the > > > > medium is writeable at all). > > > > > > Modern disks generally do this kind of thing themselves. By the time > > ^^^^^^^^^^^^ > > How many times does Stephan need to say it? 'Generally do' > > is not enough, because it means 'sometimes they dont'. > > OK, _ALL_ modern disks do.
Stop this thread, we are arguing with god.
> Name an IDE or SCSI disk on sale today that doesn't retry on write > failiure. Forget I said 'Generally do'.
IBM DMVS18V (SCSI) Maxtor ATA133 160 GB DiamondMax Plus.
Maybe they _should_, but I can tell you they in fact sometimes don't (IBM very, very seldom, Maxtor just about all the time)
> > Most filesystems *are* designed with badblock lists and such, > > it is possible to teach fs drivers to tolerate write errors > > by adding affected blocks to the list and continuing (as opposed > > to 'remounted ro, BOOM!'). As usual, this can only happen if someone > > will step forward and code it. > > > > Do you think it would be a Wrong Thing to do? > > Yes, I do. > > It achieves nothing useful, and gives people a false sense of security.
How do _you_ know that? What makes _you_ argue for what _I_ think is useful and _my_ sense of security? You are on thin ice ...
> We have moved on since the 1980s, and I believe that it is now up to > the drive firmware, or the block device driver to do this, it has no > place in a filesystem.
Interestingly I owned one of those 30 MB MFM Seagate howling drives back in the 80s. I had no errors on it until I threw it away for its unbelievable noise rate. Today I throw away one (very low-noise) disk about every week for shooting yet another fs somewhere near midnight. Indeed we moved on, only the direction looks sometimes questionable ...
Regards, Stephan
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