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List:       evms-devel
Subject:    Re: Ang: Re: [Evms-devel] About Bad Block Relocation Segment Manager
From:       Steve Dobbelstein <steved () us ! ibm ! com>
Date:       2006-01-06 21:07:44
Message-ID: OFA0254BEA.F835D36E-ON062570EE.0072DAC0-062570EE.007410C0 () us ! ibm ! com
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Ross Boylan <RossBoylan@stanfordalumni.org> wrote on 01/06/2006 12:03:19
PM:

> How would we know if BBR is catching errors?

Taking a quick look at the code:

1) I don't see any code in the EVMS BBR Segment Manager that reports if
sectors are being remapped.  That's probably because it would have to have
some way to talk to the kernel code to get the current state.

2) I don't see any code in the Device Mapper BBR target that reports if
sectors are being remapped.  However, the code does log an error when it
gets an error back from a write request.  You could check the output of
dmesg to see if BBR caught an error.  The problem is it may have caught an
error a long time ago but not one recently.  dmesg may not contain a log
entry that says BBR caught an error even though BBR is currently remapping
on certain sectors.  You could have a program monitor the log and alert the
user when BBR catches an error.  At that time the user should start taking
steps to replace the disk.  However, the alert will only happen once for
each error that BBR catches.

I don't see a way to query if BBR is currently remapping sectors.  Looks
like a good function to add.

Steve D.



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