Simulated Ordered Mode

Simulated Ordered Mode

[Al Boldi]

Filesystems are generally updated in a serial fashion:
1. Update MetaData
2. Update FileData
3. Sync...  (optional)

Is it possible to instruct the FS to delay metadata update until after a
filedata sync?
Like:
1. Buffer MetaData
2. Update FileData
3. Sync
4. Update MetaData
5. Sync...	(optional)

Ext3 offers this as an ordered mode, but could this be done on a lower level
as in bdflush?

--
Al

Re: Simulated Ordered Mode

[Martin Jambor]

On 7/31/05, Al Boldi <a1426z@gawab.com> wrote:
> Is it possible to instruct the FS to delay metadata update until after a
> filedata sync?

If you delayed any update until after a sync it wouldn't be a sync
anymore, would it?

HTH

Martin

RE: Simulated Ordered Mode

[Al Boldi]

Martin Jambor wrote: {
On 7/31/05, Al Boldi <a1426z@gawab.com> wrote:
> Is it possible to instruct the FS to delay metadata update until after 
> a filedata sync?

If you delayed any update until after a sync it wouldn't be a sync anymore,
would it?
}

True, but what about an implied MetaData sync _after_ a FileData sync?

Re: Simulated Ordered Mode

[Martin Jambor]

On 7/31/05, Al Boldi <a1426z@gawab.com> wrote:
> Martin Jambor wrote: {
> On 7/31/05, Al Boldi <a1426z@gawab.com> wrote:
> > Is it possible to instruct the FS to delay metadata update until after
> > a filedata sync?
> 
> If you delayed any update until after a sync it wouldn't be a sync anymore,
> would it?
> }
> 
> True, but what about an implied MetaData sync _after_ a FileData sync?

What do you mean by "sync?" If you mean an operation that brings an on
disk image of a filesystem into a consistent state then you cannot
delay any writeout until after it.

If you mean an ordinary update of the file (and directory) contents
then such capability must be coded at the filesystem level because
only the specific filesystem knows what are metadata and what are data
and what files different metadata belong to.

HTH

Martin