Camcontrol not changing modepage

[Kenneth D. Merry]

On Mon, Nov 13, 2006 at 13:36:34 -0500, Tuc at T-B-O-H.NET wrote:
> Hi,
> 
> 	I have a disk thats doing :
> 
> THE FOLLOWING DISK SECTORS COULD NOT BE READ: 1131461,
> 
> 	So I 
> 
> himinbjorg# camcontrol modepage da0 -m 1
> AWRE (Auto Write Reallocation Enbld):  1
> ARRE (Auto Read Reallocation Enbld):  0
> TB (Transfer Block):  1
> RC (Read Continuous):  1
> EER (Enable Early Recovery):  1
> PER (Post Error):  1
> DTE (Disable Transfer on Error):  1
> DCR (Disable Correction):  1
> Read Retry Count:  191
> Correction Span:  250
> Head Offset Count:  204
> Data Strobe Offset Count:  5
> Write Retry Count:  70
> Recovery Time Limit:  3880
> 
> 	I want to turn ARRE on, which is supposedly
> able to be re-written :
> 
> himinbjorg# camcontrol modepage da0 -m 1 -P 1
> AWRE (Auto Write Reallocation Enbld):  1
> ARRE (Auto Read Reallocation Enbld):  0

The page control value of 1 that you specified tells camcontrol to ask for
the bitmask of changeable bits in the page.

The 0, above, tells us that we cannot change the ARRE value.

> TB (Transfer Block):  1
> RC (Read Continuous):  1
> EER (Enable Early Recovery):  1
> PER (Post Error):  1
> DTE (Disable Transfer on Error):  1
> DCR (Disable Correction):  1
> Read Retry Count:  191
> Correction Span:  250
> Head Offset Count:  204
> Data Strobe Offset Count:  5
> Write Retry Count:  70
> Recovery Time Limit:  3880
> 
> 	I do the "-e" and insert in my editor :
> 
> ARRE (Auto Read Reallocation Enbld):  1
> 
> 	And I get back :
> 
> camcontrol: modepage entry "ARRE (Auto Read Reallocation Enbld)" is read-only; skipping.
> 
> 
> 	Am I doing something wrong?

That's the expected response for a bit marked read-only.  It looks like
your drive is probably broken, though.  It's returning the same values when
you set the page control field to 1 as the current values.  It should
return a bitmask instead.

What drive vendor/model is this?

In any case, it probably doesn't matter that much.  If the drive can't read
the block you're trying to read, there is a 99% likelihood that it won't be
able to do ARRE on that particular block, either.  ARRE is only useful for
blocks that can still be reconstructed with ECC information, not for blocks
that are beyond repair.

Although it would be good to turn on ARRE for any future bad blocks that
can be recovered on read.

I think the only way to do that with camcontrol for this particular drive
would probably be with 'camcontrol cmd'.  You'd have to format the CDB and
mode page by hand.  'camcontrol modepage' won't let you edit fields that
the drive says can't be edited.

Ken
-- 
Kenneth Merry
ken at kdm.org