SQL Anywhere Mobile - Slow download over modem

Author

Slow download over modem

Brian Greiman

2005-04-27, 1:24 pm

We are using ASA 9.01.1964. Server is Win32 and client is a Windows laptop.
At certain times, we are seeing very slow downloads across a modem
connection. I have included snippets from server and client logs here:

Server Log:
I. 04/26 16:03:18. <1.5> [0507]: # rows downloaded for insert/update from
table ar_open_item : 16
I. 04/26 16:03:18. <1.5> [0507]: # rows filtered for download from table
ar_open_item : 0
I. 04/26 16:03:18. <1.5> [0507]: # rows downloaded to remote from table
ar_open_item : 16
I. 04/26 16:03:18. <1.5> [0507]: COMMIT Transaction: end_download
I. 04/26 16:03:18. <1.5> [0507]: Sending the download to the remote
database.
I. 04/26 16:33:26. <1.5> [0507]: Creating download cache file
" C:\DOCUME~1\ADMINI~1
\LOCALS~1\Temp\rd000
000aa"
I. 04/26 16:33:26. <1.5> [0507]: COMMIT Transaction: end_synchronization
I. 04/26 16:33:26. <1.5> [0507]: Synchronization complete

Client Log:
I. 04/26 16:02:38. Waiting for MobiLink to apply upload
I. 04/26 16:03:24. The user authentication value is 1000.
I. 04/26 16:03:24. COMMIT
I. 04/26 16:35:06. Download stream: received 575529 bytes from MobiLink
Server.
I. 04/26 16:35:06. Processing download stream ...
I. 04/26 16:35:06. Downloading into table:
in_invoice_detail_it
em_description
I. 04/26 16:35:06. # rows inserted/updated into table
in_invoice_detail_it
em_description : 0
I. 04/26 16:35:06. # rows deleted in table
in_invoice_detail_it
em_description : 0

The client in this case is downloading 575529 bytes of information across a
modem connection (56k modem, but not sure what the connection speed was
during this session). It took 33 minutes to downlod this information, which
seems like way too long.

Can anyone give any advice on why this download phase would take so long or
steps I can take to optimize the connection. The applying of the data was
quick, it just seems like it took a long time to download. Any command-line
parameters or other advice to speed this up. Our laptops are remote and
only are in the home office about once per week.

Server command line:
dbmlsrv9 -c "dsn=central
database;dbn=central
;eng=central;uid=xxx
;pwd=xxx;commlinks=t
cpip" -zs
MLServer -x tcpip -o c:\mlserver.txt -os 5m -zu+ -za -v np -dl

Client command line:
dbmlsync -c "dsn=local
database;dbn=local;e
ng=local;uid=xxx;pwd
=xxx;commlinks=tcpip
" -u
"0507" -k -x -vn -e "FT=off" -n "pub_ml_sales" -n "pub_ml_sales_subset" -o
c:\bersys\0507.txt c:\bersys

Thanks for any help or suggestions.

Greg Fenton

2005-04-27, 8:25 pm

Brian Greiman wrote:
> I. 04/26 16:03:18. <1.5> [0507]: Sending the download to the remote
> database.
> I. 04/26 16:33:26. <1.5> [0507]: Creating download cache file
> " C:\DOCUME~1\ADMINI~1
\LOCALS~1\Temp\rd000
000aa"

Yikes! This could be a bug in the logging mechanism, but it looks like
it took 28 minutes to build the download cache?

If this log reflects reality, then this is not a modem-transfer issue.
The download is taking a long time to build, is there possibly a problem
with your server's drive?

Assuming you don't have SendDownloadACK enabled (which it isn't by
default in 8.x and 9.x), then I really think you have to look into your
consolidated and see if there is a runaway process or something similar.

greg.fenton
--
Greg Fenton
Consultant, Solution Services, iAnywhere Solutions
--------
Visit the iAnywhere Solutions Developer Community
Whitepapers, TechDocs, Downloads
http://www.ianywhere.com/developer/

Brian Greiman

2005-04-28, 1:26 pm

Does it create the cache file on the server or on the remote?
We don't have SendDownloadACK enabled.
When you say runaway process, are you talking about an external process on
server or something inside of consolidated database. I assume by the time
it is sending the download to the remote, all data has been retrieved by the
database?

Brian Greiman

"Greg Fenton" <greg. fenton_NOSPAM_@ianyw
here.com> wrote in message
news:42702cdc$1@foru
ms-1-dub...
> Brian Greiman wrote:
>
>
> Yikes! This could be a bug in the logging mechanism, but it looks like
> it took 28 minutes to build the download cache?
>
> If this log reflects reality, then this is not a modem-transfer issue.
> The download is taking a long time to build, is there possibly a problem
> with your server's drive?
>
> Assuming you don't have SendDownloadACK enabled (which it isn't by
> default in 8.x and 9.x), then I really think you have to look into your
> consolidated and see if there is a runaway process or something similar.
>
> greg.fenton
> --
> Greg Fenton
> Consultant, Solution Services, iAnywhere Solutions
> --------
> Visit the iAnywhere Solutions Developer Community
> Whitepapers, TechDocs, Downloads
> http://www.ianywhere.com/developer/

Greg Fenton

2005-04-28, 8:26 pm

Brian Greiman wrote:
> Does it create the cache file on the server or on the remote?
> We don't have SendDownloadACK enabled.
> When you say runaway process, are you talking about an external process on
> server or something inside of consolidated database. I assume by the time
> it is sending the download to the remote, all data has been retrieved by the
> database?
>

So I got some input from engineering. The creation of the "download
cache file" is indeed done *after* the download has taken place (whether
the download succeeds or fails). Note however that the cache file is
for resumable downloads (which is not what I was thinking about in my
previous post...I was thinking that the download *buffer* was taking 28
minutes to build).

So it does indeed seem that the download is taking 28 minutes to
transfer 575529 bytes. That is awfully slow, but I can't think of
anything within ML (server/client) that would cause this delay. I'm
thinking that this might simply be a problem with either your modem
connection or with the remote devices ability to write to its file store.

Can you determine the connection speed that the laptop is getting? Is
it possible that it is on a "noisy line" and therefore getting a very
slow download speed?

greg.fenton
--
Greg Fenton
Consultant, Solution Services, iAnywhere Solutions
--------
Visit the iAnywhere Solutions Developer Community
Whitepapers, TechDocs, Downloads
http://www.ianywhere.com/developer/

Brian Greiman

2005-04-28, 8:26 pm

Thanks for the reply. I will check with our end user to see to find out
more details, check connection speed, etc.

I was guessing the modem line was the issue, but wanted to make sure it
wasn't something with MobiLink.

Brian

"Greg Fenton" <greg. fenton_NOSPAM_@ianyw
here.com> wrote in message
news:42714142@forums
-2-dub...
> Brian Greiman wrote:
on[color=darkred]
time[color=darkred]
the[color=darkred]
>
> So I got some input from engineering. The creation of the "download
> cache file" is indeed done *after* the download has taken place (whether
> the download succeeds or fails). Note however that the cache file is
> for resumable downloads (which is not what I was thinking about in my
> previous post...I was thinking that the download *buffer* was taking 28
> minutes to build).
>
> So it does indeed seem that the download is taking 28 minutes to
> transfer 575529 bytes. That is awfully slow, but I can't think of
> anything within ML (server/client) that would cause this delay. I'm
> thinking that this might simply be a problem with either your modem
> connection or with the remote devices ability to write to its file store.
>
> Can you determine the connection speed that the laptop is getting? Is
> it possible that it is on a "noisy line" and therefore getting a very
> slow download speed?
>
> greg.fenton
> --
> Greg Fenton
> Consultant, Solution Services, iAnywhere Solutions
> --------
> Visit the iAnywhere Solutions Developer Community
> Whitepapers, TechDocs, Downloads
> http://www.ianywhere.com/developer/

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