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Is all Harddisk PnpDevice?
Thank You.
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:-> It's supposed to be, (PnP means only that the hard disk driver uses the PnP driver architecture, almost every driver uses the PnP driver architecture).
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Hello -
I'm working on a program that scans files on a DVD created by our product (to calculate a CRC).
When using Windows Explorer to copy from the DVD (USB connection) to my C: drive, it takes about a minutes to copy a 1GB file.
My program, however, takes close to ten minutes to read the file (doing nothing else). The following snippet demonstrates the problem:
#define HEAP_SIZE 1000000 // 1,000,000 bytes
static BYTE g_buffer[HEAP_SIZE];
hFile = CreateFile( strThisFile, GENERIC_READ, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
while ( ReadFile( hFile, g_buffer, HEAP_SIZE, &nBytesRead, NULL))
{
++nNumberOfReads;
if ( nBytesRead == 0)
{
break;
}
}Same results are observed when g_buffer is created using HeapAlloc and with varying HEAP_SIZE values.
Any hints as to why I'm seeing this are appreciated!
Thanks.
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Why do you make it hard on the system ?
- files get allocated by sectors and clusters on disk, these are all quantities that equal a power of 2. So a power of 10 for your HEAP_SIZE value is not so good.
- files get cached somehow (the file cache in RAM, and the data cache L1/L2/L3 inside or
close to the CPU chip); the hardware cache has limited size. So it probably is better to
reduce HEAP_SIZE.
I would suggest you try HEAP_SIZE values of 2^15 up to 2^18 (that's NOT C syntax !)
I expect you can get around 50 to 100 MB/s on an average system
And when organized well (two threads, ping-pong), CRC should be free.
Good luck.
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The notion that the block size should be consistent with cluster sizes makes a lot of sense.
However, I tried several sizes (65536, 262140, 1MB, 4MB) all with the same (slow) results using the USB-connected DVD drive (advertised as a "16X").
I did notice something odd, though. Currently using a 4MB block size, I put a breakpoint in my loop and found that if I stepped the program (one or two ReadFile calls per second) that the drive motor sped up.
I added a Sleep(1000) in the loop and found that my read rate went from about 1MB/sec to 4MB/sec (along with increase in motor speed). It's as if blocking on ReadFile is slowing things down. So I may experiment with overlapped IO (new to me as I spend most of my time working on embedded systems stuff).
Thanks.
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Hi,
I missed the "USB connection" in your first post. That will reduce the performance
you might hope to get to less than 40 MB/s. You should be able to reach whatever speed
Windows Explorer gives you when copying a file from DVD to HDD.
Have you tried using a FileStream ?
You could loop reading say 4KB from a FileStream and let Windows worry about the
opmization stuff, it is supposed to make the best of it...
But then, the motor speed observations are surprising. I am not familiar with DVD on USB;
I expect an optical drive to contain a cache capable of holding a couple of tracks, and to preread one track; so if you can transfer a track as fast as the disk rotates I dont
expect particular sounds...
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Haven't tried FileStream yet.
I did stumble on an interesting item: I changed my call to CreateFile thus:
hFile = CreateFile( strThisFile, GENERIC_READ, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL | FILE_FLAG_NO_BUFFERING, NULL);
The FILE_FLAG_NO_BUFFERING flag had a dramatic affect - read speeds in the 18 MB/sec range (block size also makes some difference here).
Thanks for the suggestions - they're what got me thinking.
Regards.
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Hi
CAn any body tell me how to detect the vendor id information from the usb device and
how can i know if drivers are installed for this attched usb device.
Is there any registry entry to be looked up or any device opening and messaging api need to look for.
Anybody has idea Please let me know?
sonani prakash
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Read in the MSDN about SetupAPI.txt (it is located in the Windows directory). You can set in the registry a flag so you would get a lot of information written in to SetupAPI.txt
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hiii m akhshay gandhi....
i m doin engg in information systems
can smbdy help me to connect two computers and process them together i.e parallel processing i have two PCs bbtt hw to do this is strange to me if ne1 can suggest me what to study and hw to do it will be great!!!!!
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kthxbye
Cheers,
Sebastian
--
"If it was two men, the non-driver would have challenged the driver to simply crash through the gates. The macho image thing, you know." - Marc Clifton
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hii Sebastian...
bro i don get ur answer .. can u plz explain...
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Ifuspkinsmsuwlgtitinrtrn
Expands to
if you speak in SMS you will get it in return.
I request all new posters to go through the posting manners and maintain the decorim of this community.
Coming back to your question it is highly vague if you just want to connect two PCs and do data sharing or a Higher level of data processing using parallel processors. Could you please be a bit more clear.
And before you get knocked hard refrain from using SMS
There are only two kinds of people who are really fascinating-people who know absolutely everything, and people who know absolutely nothing.
Oscar Wilde (1854-1900)
Regards...
Shouvik
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I am really sorry for using such short language, i was not aware of it. I don't want to disturb decorim of community.
Actually I want to connect two CPUs and process them together as single. Like Grid Computing.
I really don't understand from where to start for that i need some help.
Thank you sir, I assure you I try my best to maintain dignity of Forum.
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As u r saying it looks you want to chopt down a process into various resorces. But could you please throw some more light on Connecting two CPUs. If you are speaking about grids it is not only based on connection and sharing of two CPUs by a same process but many other resources like bus, ram etc are utilized. Have u given a thought to this.
Also is it you want to build a cluster or a grid please get back to us with the above details.
And bro' it was good u learnt the lesson well. Now it is your duty to pass it on to others 
There are only two kinds of people who are really fascinating-people who know absolutely everything, and people who know absolutely nothing.
Oscar Wilde (1854-1900)
Regards...
Shouvik
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shouvik.d wrote: As u r saying it looks you want to chopt down a process into various resorces.
And bro' it was good u learnt the lesson well. Now it is your duty to pass it on to others
:Cough: :Cough: See here[^]
With respect, I must disagree. A quick look at middle management in just about any corporation shows that the dodo not only survived, it's reproducing in record numbers. Christopher Duncan
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wat to see! It is my own post 
There are only two kinds of people who are really fascinating-people who know absolutely everything, and people who know absolutely nothing.
Oscar Wilde (1854-1900)
Regards...
Shouvik
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shouvik.d wrote: wat to see! It is my own post
Yea, was giving you a hard time about using sms in your post by well referencing your own post which chided that behavior. 
With respect, I must disagree. A quick look at middle management in just about any corporation shows that the dodo not only survived, it's reproducing in record numbers. Christopher Duncan
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Please try to see the context. It was meant as a reply to Akshay's SMS post. well I did get the same bashing from senior members when i was a n00b. now I m catious
There are only two kinds of people who are really fascinating-people who know absolutely everything, and people who know absolutely nothing.
Oscar Wilde (1854-1900)
Regards...
Shouvik
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shouvik.d wrote: well I did get the same bashing from senior members when i was a n00b. now I m catious
I wasn't bashing you, just giving you a hard time (in jest) that's all.
Oh and the post correcting the original poster, was well done.
With respect, I must disagree. A quick look at middle management in just about any corporation shows that the dodo not only survived, it's reproducing in record numbers. Christopher Duncan
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S Douglas wrote: Oh and the post correcting the original poster, was well done
Thanks a lot;)
Keep me burning till the End of Day!!!
There are only two kinds of people who are really fascinating-people who know absolutely everything, and people who know absolutely nothing.
Oscar Wilde (1854-1900)
Regards...
Shouvik
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Poor KID...
But best lesson you gave 
There are only two kinds of people who are really fascinating-people who know absolutely everything, and people who know absolutely nothing.
Oscar Wilde (1854-1900)
Regards...
Shouvik
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Hii Friends,
I have set a desktop machine as a Server with windows 2003 server installed and which will be up 24/7 due to file sharing requirements and web application deployed which has been used to share through Intranet.
The machine configuration is as follows
1.7 ghz, 845 Intel Chipset,
512 Ram and 60 gb harddisk
I wanted to know can i keep this machine 24/7 up. Will it impact the machine??
Nikhil Bandekar
Mumbai,
India
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Hello
Well, i'm no pro, but as far as i know major issues for servers are (in no particular order):
- Temperature (aka Heat dissipation)
- OS stability
- Component quality and thus reliability
- Power flow stability
Keeping a machine powered on 24/7 WILL impact, always.
While a usual PC gets old enough without failing machines that are on 24/7 usually fail much sooner, the only think you can do is preventing unnecessary stress on the components.
First of you need to make sure that the server is backed up through a good UPS (http://www.apcc.com).
Dirty power (also caused by Thunderstorms) can damage hard drives and almost any other component of your server. The longer the machine runs the more probable it will be that some power spike will damage your hard drives.
The next issue i would think of is heat. If your machine has a bad airflow inside the case your risk to damage your CPU or motherboard and HDs. Less heat means longer life for all components. The longer the machine is powered on the longer it components will suffer if heat inside the case is not removed through fans. 2 Big fans, in the front and on the back of the case would be a minimum i think.
I would recommend you to get a good server case (http://www.antec.com, if money ain't a big issue.
Since you already use a Server OS i guess there is nothing much to say about this, it should be pretty reliable and stable.
Last, but not least, are components.
Then components that fail soonest are HDs and PSUs (Power Supply Units).
Usually servers have 2 PSUs, when the first fails the second one jumps in and the first can be replaced. But looking at your specs i don't think you will need to worry about this.
Just keep in mind that a good and powerful PSU lives longer (if you machine consumes, say, an average of 100W and your PSU only delivers 200W MAX it will probably be dead sooner than a PSU that delivers 300W max.
What really matters here is the number of clients on your intranet.
512mb RAM and a single 60gb HD could be a bit weak.
A server OS can be pretty RAM intensive, it runs many services and has to service the clients, so 512mb RAM could turn out to be not enough for a server. Especially if there are quite a few clients logged on the server downloading data over and over again those 512mb could end used up pretty soon. I would say get another 512mb and make 1gb.
The HD is probably the weakest part of a computer, since it is still mechanical, maybe you should consider to make a simple mirror raid with two 60gb HDs.
This way preventing loss of data when you HD will fail.
Your HD will fail sooner or later, because a system that runs 24/7 fails much faster than a PC that is, if it comes up, turned on just 1/3 of a day.
Moreover if you use that server for file sharing, and you have quite some clients on your intranet, that will put your HD under particular stress. Thus producing more heat and failing sooner.
On the other hand if your intranet has only few clients and the server is only used a few times a day you can safely ignore the raid (as long as you keep backups of your data).
If your clients have to transfer data to/from the server only a few times a day you can also turn on the windows power saving for your HD. The HD will be turned of when not needed, this will help to prolong the life of the HD. This will harm performance though (since the HD needs to turn on again when a request comes in), so this is only an option if your intranet is pretty small and your server will not be used frequently.
I hope this will help you out.
Good luck
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r41n© wrote: machines that are on 24/7 usually fail much sooner
That's completely untrue. My wifes old machine was on 24/7 for over 8 years without so much as a hiccup. That machine was replaced simply because it was pretty damn old.
"Why don't you tie a kerosene-soaked rag around your ankles so the ants won't climb up and eat your candy ass..." - Dale Earnhardt, 1997
-----
"...the staggering layers of obscenity in your statement make it a work of art on so many levels." - Jason Jystad, 10/26/2001
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