> This sounds an interesting proposition for RAID 1 setups that I am using. In a couple of cases I have seen unresponsive drives retrying on a bad block seemingly to lock up my system, or at least slow response significantly.
>
> In my case I am using Seagate and Hitachi drives. A look at Wikipedia indicates that on Hitachi there is something called "Command Completion Time Limit" and on Seagate "Error Recovery Control".
>
> Please can anyone tell me how I would go about setting timeout values on these types of drive. Are there utility programs to do this or a Linux
> command.
>
> Thanks Simon.
>
> -----Original Message-----
> From:
linux-raid-owner@vger.kernel.org [mailto:linux-raid-owner@vger.kernel.org] On Behalf Of Maurice Hilarius
> Sent: 09 September 2009 02:34
> To: Mario 'BitKoenig' Holbe
> Cc: linux-raid@vger.kernel.org;
iusty@k1024.org
> Subject: Re: mdadm and TLER (Time Limited Error Recovery)
>
> Iustin Pop wrote:
>> ..
>>> Anyways, clarification...
>>> The only reason for TLER (Time Limited Error Recovery) is to behave
>>> "friendly" toward RAID controllers that timeout disks.
>>> In fact, md does not timeout disks as many Hardware RAID controllers do.
>>> So, from md's point of view, TLER is useless, i.e. it has no benefit.
>>>
>>
>> I'm sorry but I disagree here. *Especially* because md is used over
>> normal SATA controllers most of the time, TLER is beneficial because the
>> drive doesn't go catatonic for minutes at a time trying to recover a bad
>> sector, which would (because md doesn't timeout disks) cause md to hung
>> up the whole device. TLER will allow md to see the error quickly and
>> attempt to rewrite (read) or retry/fail the disk (write) for a bad the
>> sector.
>>
>> Just my understanding of the md stack.
>>
>> regards,
>> iustin
>>
>>
> I agree.
> Before WD implemented this we would see cases quite often where a
> perfectly good drive would get "kicked out"
> of a RAID as frequently or even more often, than on a hardware RAID.
> TLER management seems to have eliminated most of these cases.
>
>
>
> --
> Regards, Maurice
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