Data Transfers/Power Hinderance

NTDEV
1

Hi All
Which is the best possible way to solve the problem when there is a power
cut during a data transfer.
Say for example a Volume is getting compressed and is getting copied to a
different volume via a filter driver.
And if a power cut occurs at that time what wud be the best possible way to
continue at the point lost without corrupting any data.
The problems that we face are

  1. Copy a block of Data say 4K
  2. Compress it copy to another volume
  3. Update sector count for original partition
  4. Repeat steps 1,2,3

3 is maintained incase a user restarts the system during the process. The
process has to resume when the user logs into the system again.
This process works great without any hitch…

But when the Power goes off unexpectedly how shud the process adjust itself
such that nothing gets corrupted…
For example If power goes of after step 1 no problem.
If power goes of after step2 Big problem as the sector count has not been
updated.
If power goes of afte rstep 3 no problem again…

Hence How do do that?Any hints/suggestions?

TIA
Shal

2

When I was at IBM (many years ago), they had the same question. They said
that in OS/2 1.1, when the cord was unplugged, their data was saved. In 1.2,
data was lost. They wanted me to program a mechanism to make it work under
1.2 and 2.0. I nearly ruptured several major internal organs in the laughing
fit that ensued.

I suggested rewiring the rectifiers in the DC motor in the hard disk so that
it would use the drives spinning down to generate enough power to save that
last cache buffer :slight_smile:

To summarize: This is a serious architecture issue. I recommend going back
to the drawing board.

Jamey

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Shalini
Sent: Wednesday, August 18, 2004 8:41 AM
To: Windows System Software Devs Interest List
Subject: [ntdev] Data Transfers/Power Hinderance

Hi All
Which is the best possible way to solve the problem when there is a power
cut during a data transfer.
Say for example a Volume is getting compressed and is getting copied to a
different volume via a filter driver.
And if a power cut occurs at that time what wud be the best possible way to
continue at the point lost without corrupting any data.
The problems that we face are

  1. Copy a block of Data say 4K
  2. Compress it copy to another volume
  3. Update sector count for original partition
  4. Repeat steps 1,2,3

3 is maintained incase a user restarts the system during the process. The
process has to resume when the user logs into the system again.
This process works great without any hitch…

But when the Power goes off unexpectedly how shud the process adjust itself
such that nothing gets corrupted…
For example If power goes of after step 1 no problem.
If power goes of after step2 Big problem as the sector count has not been
updated.
If power goes of afte rstep 3 no problem again…

Hence How do do that?Any hints/suggestions?

TIA
Shal

Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256

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3

> I suggested rewiring the rectifiers in the DC motor in the hard disk so that

it would use the drives spinning down to generate enough power to save that
last cache buffer :slight_smile:

From what I know, this is really used for disk’s internal caches.

Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com

4

So is there no way to do that…!!!

Thanks

“Maxim S. Shatskih” wrote in message
news:xxxxx@ntdev…
> > I suggested rewiring the rectifiers in the DC motor in the hard disk so
that
> > it would use the drives spinning down to generate enough power to save
that
> > last cache buffer :slight_smile:
>
> From what I know, this is really used for disk’s internal caches.
>
> Maxim Shatskih, Windows DDK MVP
> StorageCraft Corporation
> xxxxx@storagecraft.com
> http://www.storagecraft.com
>
>

5

Maybe I misunderstood the OP, but doesn’t a mixture of careful writing and
logging help?