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by lsc 3890 days ago
> For example, the remapping you talk about isn't constant. It happens somewhat frequently, but reads and writes aren't constantly reordered.

the remapping I'm talking about happens when a sector goes bad. if sector 5 fails, it's remapped to the bit of disk set aside as spares, no? no secret there. but when my computer reads sector 1 through sector 10, my computer thinks it's reading sequentially... but really there's a big random seek right in the middle of it. By my understanding, that happens every time I go to read sector 5.

>Given how much the mechanical disk vendors are threatened by solid state technology, if there were a simple way to increase performance on drives, I'm sure they would provide it at this point. Even if they didn't do it for retail, their big customers would have access to it. I'm not aware of anything of the sort, so I doubt this is as big an issue as you claim.

The point here is that it's not simple, and it's not a conspiracy or anything... and a lot of this wouldn't be a win for computers running windows with a single disk, and the big customers do have access to this sort of thing; like I said, emc and netapp and the other big vendors have their own custom firmware.

My guess is that the vendors don't want to do anything that requires the user to run special software, and all the changes I'm talking about would end very badly for the user if they weren't running a filesystem/raid system that was built to handle that sort of thing.

2 comments

We have the ability to run special software and they don't give us these features. I'm sure they would if they thought would help.

On the remapping of sectors, that happens very infrequently. Look up smart reallocation count indicators for more info on this. Once a few percentage points of space has been reallocation, smart will assume the drive is failing.

You don't really need open source firmware to figure out that sector 5 is remapped. You just need a clock.