Re: SQL CE 3.5 and Data Loss on SD Card


Heck! I wouldn't downgrade either. I did not mean to even suggest that the
OP do a downgrade. I believe that the success we have had has been due to
the special care we have taken handling the connection object and making
sure the SD card is ready before we attempt data access.

Frankly the ONLY reason we have not moved forward with CF 2 and Sql CE 3.5
is that:
A) The current solution works.
B) So many other projects to get done.

If the OP can not change the way his application interfaces with the
database, I doubt there is much that can be done in the way of settings that
will prevent "days of missing data".

Ron W

"Ginny Caughey" <ginny.caughey.online@xxxxxxxxxxxxxx> wrote in message
news:8B3CD0F3-57B7-4BB6-9EB8-390B767F0A2A@xxxxxxxxxxxxxxxx
Johannes,

You might consider changing the flush interval on the connection string to
force writes to "disk" to happen more quickly. If you have the option to
move to Sqlce 3.5 sp1 that might help too. Generally I wouldn't consider
going backwards to SqlCe 2.0 to be a wise move even if you could do it and
in spite of Ron's success with it.

--

Ginny Caughey
Device Application Development MVP



"Johannes Wikman" <JohannesWikman@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in
message news:1A5A8B1B-B68A-4795-8761-EDB8DD580874@xxxxxxxxxxxxxxxx
Since we're running on the Micorosft Dynamics Mobile platform we don't
have
the option to change to Sql CE 2.0. :(

I canont change the opening/closing logic either.

So if someone knows some settings that makes Sql CE 3.5 (or 3.0) run
better
with a database on SD card I would be greatful.

/Johannes

"Ron Weiner" wrote:

I am also using Sql CE 2.0 databases that resides on SD memory cards on
a
Motorola MC50's. In nearly three years with this application on over
200
devices we have experienced only one corrupted SDF database. That
happened
when the customer attempted to open the SDF on her laptop with (drum
roll
please) Microsoft Word.

I attribute our success to opening a connection just before every DB
access
and closing it immediately afterwards. The connection object is global
for
the entire application, so it does not have to be created and destroyed
each
time data access is required. As Sql CE 2.0 is a single trick pony
(allows
only one connection at a time), I check the connection state before each
open to insure it is not already opened by another process. I also have
some code that checks to make sure the SD card is ready before
attempting
data access.

This strategy has worked well for us, and no, we have not seen any
performance issues related to the constant opening and closing of the
connection object.

Rdub

"Johannes Wikman" <JohannesWikman@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in
message news:9B2F8906-FD0C-4995-BEEA-3BEE3CB241D1@xxxxxxxxxxxxxxxx
Hi Alberto,

Do you know what settings you had to do? Were experiencing similar
problems
on MC70 devices.

Best regards,
Johannes

"Alberto Silva" wrote:

I don't remember the exact name of the control panel applet - I can
check
it
tomorow - but I do remember we had to change the SD card access from
'MMC'
to 'SD'.

Alberto Silva

"lindstjp" <lindstjp@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:ACBAB6C1-72F8-4E72-A660-B84FEE090CEB@xxxxxxxxxxxxxxxx
We are using Symbol MC9094 devices. I will check with the supplier
concerning the firmware. Do you know what settings you adjusted in
control
panel?
--
Thank you,
Jeff


"Alberto Silva" wrote:

Hi Jeff,
Are you using a consumer device or a rugged device? Do you have
the
latest
firmware on it?

The reason I ask is that some devices power down the SD card while
in
stand-by, which may lead to database corruption. We had that issue
with
Symbol MC70 devices, which was fixed with a newer firmware and
some
new
settings on the control panel.

Alberto Silva

"lindstjp" <lindstjp@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:FE586FB9-4E39-4503-B9C1-2D493EB488D7@xxxxxxxxxxxxxxxx
We have an application running on a hand device that utilizes
SQL CE
3.5
for
data storage and retrieval. The database is resides on a 2 Gig
SD
card.
We
are seeing ocassional data loss after the device is powered off
and
back
on
in the field. In testing we cannot reproduce the behavior. The
data
loss
is
significant, recently we lost about 2.5 hours worth of
transactions
from
one
database. The database itself doesn't report corrupt, it just
comes
back
on
reboot as if it cleanly rolled back all transactions. Printouts
and
user
testimony indicate it was functioning correctly prior to the
data
loss.
We
suspect the SD card may be the culprit. Any thoughts?
--
Thank you,
Jeff

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