Re: Proposal to enable WAPBL by default for 10.0
On Thu, 2020-07-23 at 05:17 +, David Holland wrote:
> On Wed, Jul 22, 2020 at 11:24:16PM +0200, Kamil Rytarowski wrote:
> > I propose to enable WAPBL ("log" in fstab(5)) by default for 10.0 and
> newer.
> > [...]
> >
> > Rationale: the default filesystem (FFS) without WAPBL is more prone to
> > data loss.
>
> It is not, unfortunately. We had WAPBL on by default some time back
> and eventually switched it off.
>
> The problem is that because it still doesn't do anything about
> journaling or preserving file contents, but runs a lot faster, it
> loses more data when interrupted.
How does that compare to the level of damage non-journaled FFS takes?
My VM was just bricked a second time because /etc/passwd was turned to
junk. I dare say that a proper metadata journaling + proper writes
(i.e. using rename() -- haven't verified whether that's done correctly)
should prevent that from happening again.
--
Best regards,
Michał Górny
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Re: Proposal to enable WAPBL by default for 10.0
On Thu, Jul 23, 2020 at 05:17:33AM +, David Holland wrote: > The problem is that because it still doesn't do anything about > journaling or preserving file contents, but runs a lot faster, it > loses more data when interrupted. Note since someone already asked: that should be read as "(journaling or preserving) file contents". -- David A. Holland dholl...@netbsd.org
Re: Proposal to enable WAPBL by default for 10.0
On Wed, Jul 22, 2020 at 11:24:16PM +0200, Kamil Rytarowski wrote:
> I propose to enable WAPBL ("log" in fstab(5)) by default for 10.0 and newer.
> [...]
>
> Rationale: the default filesystem (FFS) without WAPBL is more prone to
> data loss.
It is not, unfortunately. We had WAPBL on by default some time back
and eventually switched it off.
The problem is that because it still doesn't do anything about
journaling or preserving file contents, but runs a lot faster, it
loses more data when interrupted.
--
David A. Holland
dholl...@netbsd.org
Proposal to enable WAPBL by default for 10.0
I propose to enable WAPBL ("log" in fstab(5)) by default for 10.0 and newer.
WAPBL - Write Ahead Physical Block Logging file system journaling
More info on WAPBL in wapbl(4).
https://netbsd.gw.com/cgi-bin/man-cgi?wapbl++NetBSD-current
Rationale: the default filesystem (FFS) without WAPBL is more prone to
data loss.
A potential blocker:
http://gnats.netbsd.org/54504
panic: kernel diagnostic assertion "(wapbl_transaction_len(wl) <=
(wl->wl_circ_size - wl->wl_reserved_bytes))" failed: file
".../src/sys/kern/vfs_wapbl.c", line 1271 wapbl_end: current transaction
too big to flush
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