Re: end to end error recovery musings

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



H. Peter Anvin wrote:
> Ric Wheeler wrote:
>>
>> We still have the following challenges:
>>
>>    (1) read-ahead often means that we will  retry every bad sector at
>> least twice from the file system level. The first time, the fs read
>> ahead request triggers a speculative read that includes the bad sector
>> (triggering the error handling mechanisms) right before the real
>> application triggers a read does the same thing.  Not sure what the
>> answer is here since read-ahead is obviously a huge win in the normal
>> case.
>>
> 
> Probably the only sane thing to do is to remember the bad sectors and
> avoid attempting reading them; that would mean marking "automatic"
> versus "explicitly requested" requests to determine whether or not to
> filter them against a list of discovered bad blocks.

Some disks are doing their own "read-ahead" in the form
of a background media scan. Scans are done on request or
periodically (e.g. once per day or once per week) and we
have tools that can fetch the scan results from a disk
(e.g. a list of unreadable sectors). What we don't have
is any way to feed such information to a file system
that may be impacted.

Doug Gilbert


-
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [SCSI Target Devel]     [Linux SCSI Target Infrastructure]     [Kernel Newbies]     [IDE]     [Security]     [Git]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Linux ATA RAID]     [Linux IIO]     [Samba]     [Device Mapper]
  Powered by Linux