This message is from the T13 list server.
Curtis,
I was there for the discussions. I disagree it would defeat the
purpose. If no overlapping everred occurred, it wouldn't be a problem.
This is an exception case and would only be a problem (speed) in the case of
the mentioned overlap. Maybe we can't add exception cases to a spec that
way, I don't know. In any case, the burdon is really going to fall on the
host driver to either:
1) Insure in the current case, that the previous write data is updated to
the new data when the write command is processed in order to make sure old
data is not written to the drive and also throw away the read data since it
would also be old.
2) Make sure overlapping never occurs with FUA (best way regardless).
3) If the exception wording is used, understand the penality of issuing an
FUA with overlapped requests in the queue.
If T13 decides to spec a command that can result in data corruption, please
let me know and I will switch to SCSI drives. It would be worth the extra
money.
Gary Laatsch
[EMAIL PROTECTED]
----- Original Message -----
From: "Curtis Stevens" <[EMAIL PROTECTED]>
To: "T13 List Server" <[EMAIL PROTECTED]>
Sent: Monday, June 23, 2003 7:38 PM
Subject: Re: [t13] hmmm.. no comments?
> This message is from the T13 list server.
>
>
> Gary
>
> The wording you propose would defeat the purpose of the command. I do
> not know if you were there for the discussion. The purpose of the FUA was
> to cause critical data to be committed to the media, regardless of what is
> in the que. If you wait for a flush you are delaying the higher priority
> data. Furthermore, If you know that the area you are writing is for this
> type of critical data you can prevent the issue you are trying to solve in
> the drive... Queued FUA is not a function for everyday use, but if you
use
> it for the purpose intended it has great value. Fir instance, if power
has
> been removed from the system and you only have a few MS to store the
state,
> you would wrather not wait for the que to execute or flush, nor would you
> want to go through the very time consuming process of aborting the que.
You
> simply was the state information committed in the shortest possible time.
I
> see this as one of the main uses for queued FUA commands.
>
> ---------------------------
> Curtis E. Stevens
> 29 Dewey
> Irvine, Ca 92620
>
> Home: (949) 552-4777
> E-Mail: [EMAIL PROTECTED]
>
> The face of a child can say it all, especially the mouth part of the
face...
> ----- Original Message -----
> From: "Gary Laatsch" <[EMAIL PROTECTED]>
> To: "Curtis Stevens" <[EMAIL PROTECTED]>; "T13 List Server"
> <[EMAIL PROTECTED]>
> Sent: Monday, June 23, 2003 2:40 PM
> Subject: Re: [t13] hmmm.. no comments?
>
>
> > Curtis,
> >
> > Dropping HDD's is one of those very unsafe thing to do :-)
> >
> > My 2 cents on the whole deal is simple. Mark Vallis brought up a very
> good
> > point in his example of 2 read requests and the 1 write request in the
> queue
> > and than overlapped by a FUA Write request. The current ATAPI-7 spec
> > indicates that the FUA command shall not be released. Obviously if you
do
> > this, the result is the read data returned is in question (return the
old
> or
> > new data, the command was recieved before but processed after). Also,
the
> > queued write would request data that should be older then the data just
> > written with the FUA since the command was actually recieved before. I
> > think this is really an exception case and should be handled as such.
> >
> > My opinion is to modify the wording to the queued FUA commands to add
> > something like "if the queued FUA request overlaps a previously queued
> > command, that the queue shall be flushed....blah blah blah" or however
we
> > say it in T13 queue-ish. The biggest issue is that in this case, the
FUA
> > needs to release and it slows down because of the clean up needed to
> insure
> > data integrity. But I know that you guys will figure it out this week
up
> > there in SJ. Have fun.
> >
> > Gary Laatsch
> > [EMAIL PROTECTED]
> >
> > ----- Original Message -----
> > From: "Curtis Stevens" <[EMAIL PROTECTED]>
> > To: "T13 List Server" <[EMAIL PROTECTED]>
> > Sent: Monday, June 23, 2003 10:20 AM
> > Subject: Re: [t13] hmmm.. no comments?
> >
> >
> > > This message is from the T13 list server.
> > >
> > >
> > > I really don't think the issue is one of implementation... It looks
to
> me
> > > like there are some concerns about usage and the possibility of
> unexpected
> > > outcomes. MS clearly stated that they understood several of the
> > unexpected
> > > outcomes and still needed the capability. There are many "unsafe"
> things
> > > you can do to an HDD, but that has not prevented commands from being
> > > implemented.
> > >
> > > ---------------------------
> > > Curtis E. Stevens
> > > 29 Dewey
> > > Irvine, Ca 92620
> > >
> > > Home: (949) 552-4777
> > > E-Mail: [EMAIL PROTECTED]
> > >
> > > The face of a child can say it all, especially the mouth part of the
> > face...
> > > ----- Original Message -----
> > > From: "Eschmann, Michael K" <[EMAIL PROTECTED]>
> > > To: "T13 List Server" <[EMAIL PROTECTED]>
> > > Sent: Monday, June 23, 2003 8:23 AM
> > > Subject: RE: [t13] hmmm.. no comments?
> > >
> > >
> > > > This message is from the T13 list server.
> > > >
> > > >
> > > > My (humble?) opinion is that FUA is necessary and is not dangerous
as
> > long
> > > as a disk drive properly deals with outstanding requests.
> > > >
> > > > First off a flush is very slow, affecting system benchmark scores by
> as
> > > much as 5%. The more interesting fact is that not all drives properly
> > > support flush, where many HDD's will complete the Flush command
without
> > > writing any cached data to media just because of the desire to make
ones
> > > disk synthetically faster than somebody elses.
> > > >
> > > > FUA allows the OS to flush critical data without adversely affecting
> > > performance. The drive should be required to test all outstanding
> writes
> > > (in the queued case) and assure that the writes are ordered to
guarantee
> > no
> > > data loss. Lets take a look at a specific scenario:
> > > >
> > > > - Queued write 256 sectors to LBA 10000
> > > > - FUA write 1 sector 10001
> > > >
> > > > The 256-sector write must be written to media, or the 1 sector must
> > > over-write the same sector written by the 256 sector write in the
> devices
> > > cache. The drive must also assure that the media results in the same
> > data.
> > > I'm sure we could expand this simple case to something much more
> complex,
> > > but the basic idea remains: The drive must handle ordering such that
> > there
> > > is no data loss. I've asked once before, and I'll ask it again:
> someone
> > > offer up a more complex scenario where you believe FUA will break and
we
> > can
> > > then have a real conversation about the (de)merits of FUA.
> > > >
> > > > MKE.
> > > >
> > > >
> > > >
> > > > -----Original Message-----
> > > > From: Harlan Andrews [mailto:[EMAIL PROTECTED]
> > > > Sent: Friday, June 20, 2003 4:47 PM
> > > > To: Andre Hedrick; Steve Livaccari
> > > > Cc: Curtis Stevens; T13 List Server; [EMAIL PROTECTED]; Larry
Barras
> > > > Subject: Re: [t13] hmmm.. no comments?
> > > >
> > > >
> > > > This message is from the T13 list server.
> > > >
> > > >
> > > > I have not been present at any of the discussions, but Out-Of-Order
> > > > writes are inherently dangerous to ANY file system - not only to
> > > > journaling. Now that we have Flush Cache as a mandatory command,
why
> > > > don't we simply issue the Flush Cache to force unit access.
> > > >
> > > > I have not heard any real benefit for such a dangerous operation.
Why
> > > > would anyone even consider it ?
> > > >
> > > > ...Harlan
> > > >
> > > > on 6/19/03 10:49 PM, [EMAIL PROTECTED] wrote:
> > > >
> > > > >This message is from the T13 list server.
> > > > >
> > > > >
> > > > >
> > > > >Steve,
> > > > >
> > > > >This totally nukes and destroys write ordered operations.
> > > > >Example is the down/commit block on a journalled operation.
> > > > >
> > > > >Taking an FUA command to platter and blasting past the queue cache
> will
> > > > >destroy every bit of the security designed into any journaling file
> > > > >system.
> > > > >
> > > > >I still do not get why MicroSoft thinks there journaling NTFS of
the
> > > > >meta data in OS buffer cache will not take a hit. If I knew the OS
> my
> > > > >data was dependent on did such a "FOOLISH" operation I would find
> > > another.
> > > > >
> > > > >If T13 continues to move towards making it possible for the HOST to
> do
> > > bad
> > > > >things, then the DEVICE is even worse.
> > > > >
> > > > >We can all pack our bags and go home and switch to T10, because
> nobody
> > > > >will trust a device coming out of T13 again.
> > > > >
> > > > >Comments?
> > > > >
> > > > >Tomato Shield UP!!
> > > > >
> > > > >Andre Hedrick
> > > > >LAD Storage Consulting Group
> > > > >
> > > > >On Wed, 18 Jun 2003, Steve Livaccari wrote:
> > > > >
> > > > >> This message is from the T13 list server.
> > > > >>
> > > > >>
> > > > >>
> > > > >> All modern HDD's have a buffer for write cache that is used to
> stack
> > up
> > > > >> write data from both queued and unqueued write commands. A write
> > > command
> > > > >> followed by a flush cache command will likely not move the data
> from
> > > the
> > > > >> last write command to the media until the rest of the data is the
> > write
> > > > >> cache is written. If a write FUA command is used the data from
the
> > > write
> > > > >> FUA command will be given priority over the other data in the
write
> > > cache
> > > > >> and be written first.
> > > > >>
> > > > >>
> > > > >>
> > > > >> Regards,
> > > > >> Steve Livaccari
> > > > >>
> > > > >> Hard Drive Engineering
> > > > >> IBM Global Procurement
> > > > >> Internet: [EMAIL PROTECTED]
> > > > >> Phone (919) 543.7393
> > > > >>
> > > > >>
> > > > >>
> > > >
> > > > >
> > > > >> "Curtis Stevens"
> > > >
> > > > >
> > > > >> <[EMAIL PROTECTED] To: "T13
List
> > > Server"
> > > > ><[EMAIL PROTECTED]>
> > > > >> oo.com> cc:
> > > >
> > > > >
> > > > >> Sent by: Subject: Re:
[t13]
> > > hmmm..
> > > > no
> > > > >comments?
> > > > >> [EMAIL PROTECTED]
> > > >
> > > > >
> > > > >> rg
> > > >
> > > > >
> > > > >>
> > > >
> > > > >
> > > > >>
> > > >
> > > > >
> > > > >> 06/17/2003 11:09
> > > >
> > > > >
> > > > >> PM
> > > >
> > > > >
> > > > >>
> > > >
> > > > >
> > > > >>
> > > >
> > > > >
> > > > >>
> > > > >>
> > > > >>
> > > > >>
> > > > >> This message is from the T13 list server.
> > > > >>
> > > > >>
> > > > >> Gary
> > > > >>
> > > > >> As I recall, there were some inacuracies in the proposals as
> made
> > > to
> > > > >> the
> > > > >> committee. There were many revisions. The only new FUA commands
> > that
> > > make
> > > > >> sense are the queued ones. All others could be followed by flush
> > > cache.
> > > > >>
> > > > >> ---------------------------
> > > > >> Curtis E. Stevens
> > > > >> 29 Dewey
> > > > >> Irvine, Ca 92620
> > > > >>
> > > > >> Home: (949) 552-4777
> > > > >> E-Mail: [EMAIL PROTECTED]
> > > > >>
> > > > >> The face of a child can say it all, especially the mouth part of
> the
> > > > >> face...
> > > > >> ----- Original Message -----
> > > > >> From: "Gary Laatsch" <[EMAIL PROTECTED]>
> > > > >> To: "Curtis Stevens" <[EMAIL PROTECTED]>; "T13 List Server"
> > > > >> <[EMAIL PROTECTED]>
> > > > >> Sent: Tuesday, June 17, 2003 4:40 PM
> > > > >> Subject: Re: [t13] hmmm.. no comments?
> > > > >>
> > > > >>
> > > > >> > Curtis and Hale,
> > > > >> >
> > > > >> > Also, to expand upon this. I think Hale's point is the
> > proposal
> > > put
> > > > >> > forth by Nita didn't contain the QUEUE FUA or QUEUE FUA EXT
> > commands
> > > and
> > > > >> he
> > > > >> > was wondering where they were added or how they were proposed.
My
> > > memory
> > > > >> was
> > > > >> > this was discussed and added at the June 2002 meetings. That
is
> > why
> > > I
> > > > >> was
> > > > >> > wondering if anyone else remembered these discussions. I
> remember
> > > > >> > discussing all of this stuff (even Andre's comments about the
FUA
> > > blowig
> > > > >> > away the queue) but for some reason it just wasn't captured
very
> > well
> > > in
> > > > >> the
> > > > >> > minutes.
> > > > >> >
> > > > >> > Gary Laatsch
> > > > >> > [EMAIL PROTECTED]
> > > > >> >
> > > > >> > ----- Original Message -----
> > > > >> > From: "Curtis Stevens" <[EMAIL PROTECTED]>
> > > > >> > To: "T13 List Server" <[EMAIL PROTECTED]>
> > > > >> > Sent: Tuesday, June 17, 2003 3:15 PM
> > > > >> > Subject: Re: [t13] hmmm.. no comments?
> > > > >> >
> > > > >> >
> > > > >> > > This message is from the T13 list server.
> > > > >> > >
> > > > >> > >
> > > > >> > > Hale
> > > > >> > >
> > > > >> > > I was there during the discussions and there was no
secret
> > > > >> committee.
> > > > >> > > Basically, MS stated that they wanted to force meta data to
the
> > > drive
> > > > >> > > without blowing the que. This means that although it is
> possible
> > > to
> > > > >> lose
> > > > >> > > data, in their application data loss would not occur...
> > > > >> > >
> > > > >> > > ---------------------------
> > > > >> > > Curtis E. Stevens
> > > > >> > > 29 Dewey
> > > > >> > > Irvine, Ca 92620
> > > > >> > >
> > > > >> > > Home: (949) 552-4777
> > > > >> > > E-Mail: [EMAIL PROTECTED]
> > > > >> > >
> > > > >> > > The face of a child can say it all, especially the mouth part
> of
> > > the
> > > > >> > face...
> > > > >> > > ----- Original Message -----
> > > > >> > > From: "Hale Landis" <[EMAIL PROTECTED]>
> > > > >> > > To: "T13 List Server" <[EMAIL PROTECTED]>
> > > > >> > > Sent: Tuesday, June 17, 2003 10:57 AM
> > > > >> > > Subject: [t13] hmmm.. no comments?
> > > > >> > >
> > > > >> > >
> > > > >> > > > This message is from the T13 list server.
> > > > >> > > >
> > > > >> > > >
> > > > >> > > > I'm curious why there are no comments about the question of
> the
> > > > >> > > > origin of the WRITE DMA QUEUED FUA command (where is the
> > > proposal?).
> > > > >> > > > And why no comments on QUEUED EXT commands with large
sector
> > > counts.
> > > > >> > > >
> > > > >> > > > Is this because all these discussions must take place via
the
> > > "secret
> > > > >> > > > society"?
> > > > >> > > >
> > > > >> > > > Hale
> > > > >> > > >
> > > > >> > > >
> > > > >> > > >
> > > > >> > > > *** Hale Landis *** www.ata-atapi.com ***
> > > > >> > > >
> > > > >> > > >
> > > > >> > >
> > > > >>
> > > > >>
> > > > >>
> > > > >>
> > > > >>
> > > > >
> > >
>
