Re: [patch 7/12] s390: fba dasd i/o errors.

[Denis Vlasenko]

On Tuesday 12 July 2005 13:36, Martin Schwidefsky wrote:
> > > @@ -354,6 +354,8 @@ dasd_fba_build_cp(struct dasd_device * d
> > >          }
> > >          cqr->device = device;
> > >          cqr->expires = 5 * 60 * HZ;         /* 5 minutes */
> > > +        cqr->retries = 32;
> >
> > 2..4 maybe, but 32? This isn't tiny by any account.
> 
> Are you arguing the use of the adjective "tiny" or the technical
> aspects of using 32 as the number of retries for dasd fba?
> In the dasd driver we use a retry count of 255 as "standard", so
> 32 is indeed much smaller than that. If you can call it tiny,
> well who cares??

I meant that 32 retries is too many. Retries tend to multiply.
If OS does N retries per failed attempt and disk drive does M
attempts per attempt, you end up with N*M retries.
Add a few 'retrying' layers, and you have a 'I cannot umount
this fscking scratched CDROM, maybe tomorrow' type disaster.

It's better to err to the smaller number of attempts.
--
vda

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