Faster Way To Populate Micro SD Card?

[(PeteCresswell)]

"MicroSDXC Class 10 UHS-1 Memory Card".

Claimed transfer rate = 30 MB/Sec.

Let's say it's really 20 MB/Sec.

Plugging it into a USB adapter and copying a 12-gig movie to it, the
copy takes about 30 minutes. This promises to be a recurrent task as
I load up my 10.1" tablet with a movie or three preparatory to taking a
trip.

Same copy SATA-disc-to-SATA-disc takes about 5 minutes.

Seems like a 20 MB/Sec transfer speed could support a copy time of about
10 minutes if the pipeline were fast enough.

My guess is that USB is the bottleneck and an eSATA reader might give me
that 10-minute transfer time - or something close to it.

Before I blow seventy bucks on an eSATA-connected card reader as in
http://tinyurl.com/89twp43... Can anybody comment on my reasoning?

 

[Ken Springer]

"MicroSDXC Class 10 UHS-1 Memory Card".

Claimed transfer rate = 30 MB/Sec.

Let's say it's really 20 MB/Sec.

Plugging it into a USB adapter and copying a 12-gig movie to it, the
copy takes about 30 minutes. This promises to be a recurrent task as
I load up my 10.1" tablet with a movie or three preparatory to taking a
trip.

Same copy SATA-disc-to-SATA-disc takes about 5 minutes.

Seems like a 20 MB/Sec transfer speed could support a copy time of about
10 minutes if the pipeline were fast enough.

My guess is that USB is the bottleneck and an eSATA reader might give me
that 10-minute transfer time - or something close to it.

Before I blow seventy bucks on an eSATA-connected card reader as in
http://tinyurl.com/89twp43... Can anybody comment on my reasoning?

Just a question, Pete...

Can you network your computer and tablet, and transfer over the network?


--
Ken

Mac OS X 10.8.2
Firefox 18.0.2
Thunderbird 17.0.2
LibreOffice 3.6.5.2

 

[Ken Springer]

Networking would not be faster unless you have high end devices over Gigabit
Ethernet.

Assume 100Mb/s Ethernet in Full-Duplex mode. That's 200Mb/s. That's 25MB's
theotetical. Add protocol overhead and that's 20MB/s overhead theoretical.
If its Half-Duplex then that's 10MB/s. But in-practice results will be
slower so one shouldn't expect Ethernet to be faster than a physical file
transfer to media.

Thinking about it, he'd be better off using a 7200rpm SATA hard disk
connected via eSATA.

But then he could drag and drop the files to transfer, and walk away and
do something else. Never have to come back and switch the external unit
to a different computer/tablet.

--
Ken

Mac OS X 10.8.2
Firefox 18.0.2
Thunderbird 17.0.2
LibreOffice 3.6.5.2

 

[(PeteCresswell)]

Per Ken Springer:

Can you network your computer and tablet, and transfer over the network?

David's "10 MB/s write" observation seems to have this thread moot.

But, just for the record, I tried to do a copy with the tablet
USB-attached but am having some sort of problem where Windows shows
MyComputer\GT-N8013\Card (where "GT-N8013" is the name of the tablet)
and will open a window if I double-click it... but the window is
empty... i.e. no files listed - as if the card were empty - which it is
not.

Got to wonder if it's some sort of exFAT issue. I just today applied
the KB955704 update that adds exFAT capability, formatted the SD card to
exFAT, and then restored it's files from backup.

Works OK in the tablet, allows me to copy files to it when it's in a USB
adapter, but looks empty from XP when I look at it within the tablet.

 

[VanguardLH]

"MicroSDXC Class 10 UHS-1 Memory Card".

Missing the details again. That's the generic specs for the device, not
a brand and model. No one yet knows WHICH device you actually have. I
picked one from a Google search and chose:

http://www.bhphotovideo.com/bnh/controller/home?O=&sku=886007&Q=&is=REG&A=details

Notice its specs say:

Read: 30 MB/s
Write: 10 MB/s

Either mention WHOSE device you are asking about or give a URL to it.

Claimed transfer rate = 30 MB/Sec.
Let's say it's really 20 MB/Sec.

12 GB = 12 x 2^30 bytes = 12,884,901,888 bytes

30 MB/s = 30 x 2^20 bytes/sec = 31,457,280 bytes/sec

12,884,901,888 bytes / (31,457,380 bytes/min) = 409.6 sec

409.6 sec x (1 min/60 sec) = 6.8 minutes

Plugging it into a USB adapter and copying a 12-gig movie to it,

So you were *writing* to the device. That means you get the 10 MB/s
transfer rate, NOT the 30 MB/s rate.

the
copy takes about 30 minutes.

30 minutes / 6.8 minutes = 4.4

You copy is taking more than 4 times longer than the specified transfer
rate for the device. EXCEPT that is for a read transfer and that is not
what you described. Instead you are writing to the device so you don't
get 30 MB/s but only 10 MB/s. Instead of being 4.4 times slower than
expect, the device is only 4.4 / (30 Mbps/10 Mbps) = 1.5 times slower.
The above calculations for 6.8 minutes to transfer 12 GB was at your
claimed 30 MB/s transfer rate. Since the transfer rate for a WRITE
which is what you are doing is a third of that speed (only 10 MB/s) then
the time to transfer would be 3 times longer, or 20.4 minutes.

30 minutes / 20.4 minutes = 1.5

The actual transfer rate is severely less than the published transfer
rate but it is still significantly different (50% more than published).

So what anti-virus program are you using? Did you disable it for the
huge file transfer? I've noticed that when WSUS offline (a means of
collecting updates for Windows & Office and storing them locally)
downloads a huge file that the process crawls because of the
interference by the AV program to interrogate EVERY single byte during
the transfer. If I temporarily disable the AV program, the file copy
goes very quickly.

This promises to be a recurrent task as
I load up my 10.1" tablet with a movie or three preparatory to taking a
trip.

Does the tablet have an anti-virus program, or other security software
that interrogates file creates and modifies?

Same copy SATA-disc-to-SATA-disc takes about 5 minutes.

Seems like a 20 MB/Sec transfer speed could support a copy time of about
10 minutes if the pipeline were fast enough.

My guess is that USB is the bottleneck and an eSATA reader might give me
that 10-minute transfer time - or something close to it.

USB 1.x:
Low bandwidth: 1.5 Mbps (187 KBps)
Full bandwidth: 12 Mbps (1.5 MBps)

USB 2.0:
Max signalling rate: 480 Mbps
(effective throughput of 280 Mbps or 35 MBps)

So it looks like the device supports USB 2.x. It also looks like you
couldn't distinguish between read and write speeds for the device -- but
then we don't know WHICH device you're asking about since you never
identified make and model. Plus there may be an AV program further
slowing the writes.

Before I blow seventy bucks on an eSATA-connected card reader as in
http://tinyurl.com/89twp43... Can anybody comment on my reasoning?

See what happens when you temporarily disable all your security
software, especially whatever anti-virus program you are using.

 

[(PeteCresswell)]

Per David H. Lipman:

Can you rephrase and amplify on the above about "...copy with the tablet
USB-attached but am having some sort of problem where Windows...".

The SD card functions as expected when it is accessed from the tablet's
OS.

But when Windows XP connects to the tablet and the card is opened within
a Windows Explorer window, the card looks empty.

 

[J. P. Gilliver (John)]

In message <[email protected]>, VanguardLH <[email protected]>
writes:
[]

You copy is taking more than 4 times longer than the specified transfer
rate for the device. EXCEPT that is for a read transfer and that is not
what you described. Instead you are writing to the device so you don't
get 30 MB/s but only 10 MB/s. Instead of being 4.4 times slower than
expect, the device is only 4.4 / (30 Mbps/10 Mbps) = 1.5 times slower.
The above calculations for 6.8 minutes to transfer 12 GB was at your
claimed 30 MB/s transfer rate. Since the transfer rate for a WRITE
which is what you are doing is a third of that speed (only 10 MB/s) then
the time to transfer would be 3 times longer, or 20.4 minutes.

30 minutes / 20.4 minutes = 1.5

What a long-winded way of saying it's only going at 1/1.5 the speed
expected.
[]

USB 1.x:
Low bandwidth: 1.5 Mbps (187 KBps)
Full bandwidth: 12 Mbps (1.5 MBps)

USB 2.0:
Max signalling rate: 480 Mbps
(effective throughput of 280 Mbps or 35 MBps)

So it looks like the device supports USB 2.x. It also looks like you

[]

 

[VanguardLH]

What a long-winded way of saying it's only going at 1/1.5 the speed
expected.

And then someone says "prove it". If I choose to qualify my response
then why are you bitching? Because you're too lazy to read? Then
don't. Even you should know how to skip through a document by fast
scanning to look for keywords or phrases that truly interest you.

I'm quite well known for being verbose. If long posts are intolerable
to you then filter out my posts. If you used a decent newsreader then
you might even filter by the number of lines in a post.

 

[J. P. Gilliver (John)]

What a long-winded way of saying it's only going at 1/1.5 the speed
expected.

And then someone says "prove it". If I choose to qualify my response[/QUOTE]

Do so when they do.

then why are you bitching? Because you're too lazy to read? Then
don't. Even you should know how to skip through a document by fast
scanning to look for keywords or phrases that truly interest you.

I'm quite well known for being verbose. If long posts are intolerable
to you then filter out my posts. If you used a decent newsreader then
you might even filter by the number of lines in a post.

I responded out of friendship, because I see a lot of myself in your
verbosity - in other words, I see you doing what I tend to do too!

It does tend to obscure the essential point(s) of what one is trying to
say if you (and I!) give too much supporting information: people glaze
over, and tend to as you suggest skip the posts altogether, rather than
dig into them for the detail.

FWIW, I currently have no intention of killfiling you! (I do have the
ability to kill based on number of lines, but that is rather a bludgeon
method, and doesn't distinguish between verbose and long, which are not
always the same thing.)
--
J. P. Gilliver. UMRA: 1960/<1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

"The people here are more educated and intelligent. Even stupid people in
Britain are smarter than Americans." Madonna, in RT 30 June-6July 2001 (page
32)