skipping fsck with soft-updates enabled

[Victor Loureiro Lima]

>From rc.conf man page:
---
 background_fsck_delay
                 (int) The amount of time in seconds to sleep before starting
                 a background fsck(8).  It defaults to sixty seconds to allow
                 large applications such as the X server to start before disk
                 I/O bandwidth is monopolized by fsck(8).
---

 You can set the delay as long as you want, so it wont have to start
right away, in fact it can start as late as a year (if thats really
what you want ;))

att,
victor loureiro lima

2007/1/10, Oliver Fromme <olli at lurza.secnetix.de>:
> Scott Oertel wrote:
>  > I am wondering what kind of problems would occur, besides lost space, if
>  > after a system crash a fsck is skipped. According to the documentation,
>  > with soft-updates enabled, the file system would be consistant, there
>  > would just be lost resources to be recovered which I am assuming can be
>  > safely done at a later time to avoid long periods of downtime during
>  > peek hours.
>
> I think that's exactly what the background fsck feature
> does.  If you enable it (which is even the default), the
> fsck process doesn' start right away, so the system comes
> up in multi-user mode immediately.  Then a snapshot is
> created on the file system, and fsck runs on the snap-
> shot, freeing the lost space in the file system.
>
> Of course, it only works reliably with soft-updates enabled,
> _and_ there must not be any unexpected inconsistencies.
> However, with some common setups (e.g. cheap disks lying
> about completed write operation) it is difficult to
> guarantee the consistency.  Soft-updates is rather fragile
> when the hardware doesn't work exactly as it's supposed to.
> I've witnessed breakage in the past, and for that reason
> I always disable the background fsck feature.  And it's the
> reason I'm looking forward to gjournal to become stable,
> because it seems to be less fragile in the presence of
> imperfect hardware.
>
> Best regards
>    Oliver
>
> --
> Oliver Fromme,  secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing
> Dienstleistungen mit Schwerpunkt FreeBSD: http://www.secnetix.de/bsd
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> and may not necessarily reflect the opinions of secnetix in any way.
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