Slow write to sqlite on usb sticks

[Terry Judd]

Interesting stats Kay. I have a feeling that not all USB memory sticks are equal either. The no-name ones we give out to students (8 GB) are relatively cheap and definitely don't perform as well as a couple of name brand sticks I have lying around.

I don't think we even get close to 11 MB/s out of these cheapies.

Terry...

On 26/04/2012, at 6:59 PM, "Kay C Lan" <lan.kc.macmail at gmail.com> wrote:

> Hi Terry,
> 
> Strange you should raise this as I was just wondering myself why SD cards
> are so slow when they have no mechanical parts. You don't mention if the HD
> you were using was internal or external, but on my own system I get the
> following benchmarks:
> 
> Internal HD - 99 MB/s
> External eSATA (via cardbus adapter) - 81 MB/s
> External FW800 - 58 MB/s
> Exernal FW400 - 32 MB/s *
> External USB 2.0 - 26 MB/s *
> SD Card (via card bus adaptor) - 11 MB/s
> 
> * same HD, same enclosure, dual port.
> 
> I've seen a youTube video (so it must be true;-) which showed a benchtest
> between a USB stick and an SD card and the USB stick was about 1 MB/s
> slower. I don't have a usb stick to benchtest, but because of the video,
> when I bought my last SD card it was the fasted I could find - they have a
> speed rating which I can't recall right now.
> 
> The above is not accurate because to be a true test of bus interface speed
> the HD should be the same, and in this case I've used 3 different HDs, 1 x
> Internal, 1 x eSATA & FW800, and the last one in a dual port enclosure.
> 
> I believe though that it gives a ball park figure of what you can expect,
> and so anacdotally a USB stick is about 10 times slower than an internal
> HD. This doesn't fully explain your performance drop, but I believe it
> explains a good portion of it.
> 
> It also explains why downloading photos off the SD card takes soooooo
> loooooonnnnggggggggg......
> 
> I still don't understand why though.... there are no moving parts?
> 
> On Thu, Apr 26, 2012 at 9:57 AM, Terry Judd <terry.judd at unimelb.edu.au>wrote:
> 
>> We're finding that it's very slow to write even small amounts of data from
>> Livecode to a sqlite file when the Livecode app and the db file are on a
>> usb stick (the db stores a local copy of the user's messages as they are
>> downloaded from a server). It seems to be something that is peculiar to the
>> usb setup as it works very quickly when run from a hard drive (less that 1
>> second for 40 messages vs 20-30 seconds on the usb stick). Has anyone
>> experienced anything similar and/or does anyone have any suggestions as to
>> how we might speed the process up?
>> 
>> I'm currently downloading the messages (as xml), converting them to an
>> array (from, to, subject, body, attachments etc.) and then writing each to
>> the sqlite db within a repeat loop and then closing the db connection.
>> 
>> Terry...
>> 
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