zfs discuss - Aug 2007 - ZFS, ZIL, vq_max_pending and OSCON

The slides from my ZFS presentation at OSCON (as well as some  
additional information) are available at http://www.meangrape.com/ 
2007/08/oscon-zfs/

Jay Edwards
jay at meangrape.com
http://www.meangrape.com


-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://mail.opensolaris.org/pipermail/zfs-discuss/attachments/20070802/f2fa7b08/attachment.html>

Hello Jay,

Thursday, August 2, 2007, 8:10:52 AM, you wrote:

>

The slides from my ZFS presentation at OSCON (as well as some additional
information) are available at http://www.meangrape.com/2007/08/oscon-zfs/

I can''t find the actual link to your presentation...

-- 

Best regards,

 Robert                            mailto:rmilkowski@task.gda.pl

                                       http://milek.blogspot.com


_______________________________________________
zfs-discuss mailing list
zfs-discuss@opensolaris.org
http://mail.opensolaris.org/mailman/listinfo/zfs-discuss

For a while I had the same problem ;-)

Turns out the link is not at "my presentation" but
way down at the bottom where it says "My slides are here"

replicated here for your use:

http://www.meangrape.com/wp-content/uploads/2007/08/OSCON_zfs.pdf

- Chris

> Hello Jay,
> 
> 
> Thursday, August 2, 2007, 8:10:52 AM, you wrote:
> 
> 
>>
> 
> 	
> 
> The slides from my ZFS presentation at OSCON (as well as some additional 
> information) are available at http://www.meangrape.com/2007/08/oscon-zfs/
> 
> 
> 
> 
> 
> I can''t find the actual link to your presentation...
> 
> 
> -- 
> 
> Best regards,
> 
>  Robert                            mailto:rmilkowski at task.gda.pl
> 
>                                        http://milek.blogspot.com
> 
> 
> ------------------------------------------------------------------------
> 
> _______________________________________________
> zfs-discuss mailing list
> zfs-discuss at opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss

Jay,

Slides look good, though I''m not not sure what you say along
with "Filthy lying" on slide 22 related to the ZIL, or
slide 27 which has "Worst Feature - thinks hardware is stupid".

Anyway I have some comments on http://www.meangrape.com/2007/08/oscon-zfs
You say:
-------
Records in the ZIL are discarded in a number of circumstances:

    * a DMU transaction group completes and is committed to stable storage
    * a write flagged O_DSYNC completes
    * an fsync() call is completed
    * a ZFS filesystem is successfully unmounted
----

Your fist bullet is correct: in-memory and stable storage intent log
records are discarded when the dmu transaction group is committed
to stable storage. However, this is the only time they are discarded.

A O_DSYNC or fsync will cause in-memory records to be written to the
stable storage intent log. When unmounting, if there are any uncommitted
transactions we wait for that DMU transaction group to commit.

Most of this is explained in:

http://blogs.sun.com/perrin/entry/the_lumberjack

Hope that helps: Neil.

Jay Edwards wrote:
> The slides from my ZFS presentation at OSCON (as well as some additional 
> information) are available at _http://www.meangrape.com/2007/08/oscon-zfs/_
> 
> Jay Edwards
> jay at meangrape.com <mailto:jay at meangrape.com>
> http://www.meangrape.com
> 
> 
> 
> ------------------------------------------------------------------------
> 
> _______________________________________________
> zfs-discuss mailing list
> zfs-discuss at opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss