Re: why does raidframe retry I/O 5 times

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Mon, Jun 25, 2012 at 09:39:45AM -0700, Brian Buhrow wrote:
>       Hello.  While I agree with Manuel's assertion that the system becomes
> stalled while all these retries are happening, I actually like all the
> retries, because I've actually seen drives finally wake up and either remap
> and write sectors they were complaining about, or figure out how to correct
> the read error they were getting and deliver the data.  FreeBSD times out
> much more quickly and loses drives seemingly more often.  I'd rather see

In my experience, if a wd(4) drive couldn't get the data after 5
retries, it's very unlikely it will get it after 25.

> the wd(4) and raidframe(4) drivers made mp save which I think will address
> the stalling issue, mostly, while retaining the persistent nature of the
> current scheme.

No, it won't. While a drive is retrying, I/O to this drive are
stalled (obviously). 25 retries stalls I/O to this drive for 25 seconds,
which stalls anything else which also needs this drive for 25 seconds.

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--