What Is Ideal Buffer Size?

When setting up my soundcard with Audition 3 (under Preferences/Audio Hardware) it asks for I/O Buffer Size.
It was automatically on 512. Is this an ideal setting for a 1 mic, VO setup?
Thanks!

Hi,
The NI-USB devices have a totaly different approach for buffering write and read operations, then our Plug In boards. because it is USB , the driver buffers all the frames for Write operations in Host memory. For Read operations there is a small memory at the device but the driver transfers as fast as possible and buffers the frames in Host memory as well.
Thus you do not need to configure queues with the config function at all. I have not seen a overflow error so far, even with Full Speed USB.
Hope that helps.
DirkW

Similar Messages

Based on my computer what I/O buffer size and process buffer should I have to stop getting the system too slow error message?

I need some sugestions on my settings. I have a 13 in macbook pro runnig 10.8.2 with a 2.7 Ghz i7 with 4 GB of ram.
I am using Logic pro X 10.0.3 and when I get to a really load heavy section of a project then I get a too slow error message.
I know this will happen from time to time because of my computer but is there anyway to make it better?

Im curious how you are running LPX on an OS X 10.8.2 system?
As to your question.. there is no specific answer... Try playing with the settings (making a note of your current ones) and see what improvements, if any, are made under different combinations of the settings.
Personally I'd add more RAM if you can... as that alone may help matters by some degree...
Finally,
This article may also help.. (Its written for LP9 but most of it is applicable for LPX too)
http://support.apple.com/kb/TA24535

VISA Set I/O Buffer Size fails with all but one value on Linux RT

I was unable to initialize a serial port on a cRIO-9030 using a code that works fine on VxWorks and Windows, when I tracked it down to this somewhat strange behaviour;
If you call VISA Set I/O Buffer Size on Linux RT (at least on the 9030 device) you will get error code 1073676424 for all size values other than 0.
That is a bit strange (what will the buffer size be then I might add...), but something even uglier is that if you leave the function's buffer size unwire, you will also get the error (because the function's default is 4096).
MTO

Under the hood VISA is using the POSIX serial interface for Mac OS X (same as for Linux and Solaris). This interface does not support changing the buffer size. Hence, the buffer size is fixed to the internal OS buffer size. The only thing that changing the buffer size will do (for the out buffer) is to have VISA not flush the data after every write. This is a limitation in the serial API for Mac OS X. Therefore, VISA reports a warning.

Determining the max allowable buffer size

I am working on a program which works with very large amounts of data. Each job that is processed requires the program to read through as many as several hundred files, each of which has tens of thousands of values. The result of the operation is to take the data values in these files, rearrange them, and output the new data to a single file. The problem is with the new order of the data. The first value in each of the input files (all several hundred of them) must be output first, then the 2nd value from each file, and so on. At first I tried doing this all in memory, but for large datasets, I get OutOfMemoryErrors. I then rewrote the program to first output to a temporary binary file in the correct order. However, this is a lot slower. As it processes one input file, it must skip all around in the output file, and do this several hundred times in a 60+ MB file.
I could tell it to increase the heap size, but there is a limit to how much it will let me give it. I'd like to design it in a way so that I could allocate as big of a memory buffer as I can, read through all the files and put as much data in as it can into the buffer, output the block of data to the output file, and then run through everything again for the next block.
So my question is, how do I determine the biggest possible byte buffer I can allocate, yet still have some memory left over for the other small allocations that will need to be done?

The program doesn't append, it has to write data to the binary file out of order because the order that it reads data from the input files is not in the order that it will need to be output. The first value from all of the input files have to be output first, followed by the second value from every input file, and so on. Unless it is going to have several hundred input files open at once, the only way to output it in the correct order is to jump around the output file. For example, say that there are 300 input files with double values. The program opens the first input file, gets the first value and outputs at position 0. Then it reads the second value and must write it to position 300 (or byte position 8*300 considering the size of a double). The third value must go to position 600, and so on. That is the problem, it must output the values in a different order than it reads them.
Without giving any VM parameters to increase the heap size, Java will let me create a byte buffer of 32MB in size, but not much more. If the data to be output is more than 32MB, I will need to work on the data in 32MB chunks. However, if the user passes VM parameters to increase the heap size, the program could create a larger buffer to work on bigger chunks and get better performance. So somehow I need to find out what a reasonable buffer size is to get the best performance.

What's the optimum buffer size?

Hi everyone,
I'm having trouble with my unzipping method. The thing is when I unzip a smaller file, like something 200 kb, it unzips fine. But when it comes to large files, like something 10000 kb large, it doesn't unzip at all!
I'm guessing it has something to do with buffer size... or does it? Could someone please explain what is wrong?
Here's my code:
import java.io.*;
import java.util.zip.*;
* Utility class with methods to zip/unzip and gzip/gunzip files.
public class ZipGzipper {
public static final int BUF_SIZE = 8192;
public static final int STATUS_OK = 0;
public static final int STATUS_OUT_FAIL = 1; // No output stream.
public static final int STATUS_ZIP_FAIL = 2; // No zipped file
public static final int STATUS_GZIP_FAIL = 3; // No gzipped file
public static final int STATUS_IN_FAIL = 4; // No input stream.
public static final int STATUS_UNZIP_FAIL = 5; // No decompressed zip file
public static final int STATUS_GUNZIP_FAIL = 6; // No decompressed gzip file
private static String fMessages [] = {
 "Operation succeeded",
 "Failed to create output stream",
 "Failed to create zipped file",
 "Failed to create gzipped file",
 "Failed to open input stream",
 "Failed to decompress zip file",
 "Failed to decompress gzip file"
 * Unzip the files from a zip archive into the given output directory.
 * It is assumed the archive file ends in ".zip".
public static int unzipFile (File file_input, File dir_output) {
 // Create a buffered zip stream to the archive file input.
 ZipInputStream zip_in_stream;
 try {
 FileInputStream in = new FileInputStream (file_input);
 BufferedInputStream source = new BufferedInputStream (in);
 zip_in_stream = new ZipInputStream (source);
 catch (IOException e) {
 return STATUS_IN_FAIL;
 // Need a buffer for reading from the input file.
 byte[] input_buffer = new byte[BUF_SIZE];
 int len = 0;
 // Loop through the entries in the ZIP archive and read
 // each compressed file.
 do {
 try {
 // Need to read the ZipEntry for each file in the archive
 ZipEntry zip_entry = zip_in_stream.getNextEntry ();
 if (zip_entry == null) break;
 // Use the ZipEntry name as that of the compressed file.
 File output_file = new File (dir_output, zip_entry.getName ());
 // Create a buffered output stream.
 FileOutputStream out = new FileOutputStream (output_file);
 BufferedOutputStream destination =
 new BufferedOutputStream (out, BUF_SIZE);
 // Reading from the zip input stream will decompress the data
 // which is then written to the output file.
 while ((len = zip_in_stream.read (input_buffer, 0, BUF_SIZE)) != -1)
 destination.write (input_buffer, 0, len);
 destination.flush (); // Insure all the data is output
 out.close ();
 catch (IOException e) {
 return STATUS_GUNZIP_FAIL;
 } while (true);// Continue reading files from the archive
 try {
 zip_in_stream.close ();
 catch (IOException e) {}
 return STATUS_OK;
} // unzipFile
} // ZipGzipperThanks!!!!

Any more hints on how to fix it? I've been fiddling
around with it for an hour..... and throwing more
exceptions. But I'm still no closer to debugging it!
ThanksDid you add:
e.printStackTrace();
to your catch blocks?
Didn't you in that case get an exception which says something similar to:
java.io.FileNotFoundException: C:\TEMP\test\com\blah\icon.gif (The system cannot find the path specified)
 at java.io.FileOutputStream.open(Native Method)
 at java.io.FileOutputStream.<init>(FileOutputStream.java:179)
 at java.io.FileOutputStream.<init>(FileOutputStream.java:131)
 at Test.unzipFile(Test.java:68)
 at Test.main(Test.java:10)Which says that the error is thrown here:
 // Create a buffered output stream.
 FileOutputStream out = new FileOutputStream(output_file);Kaj

Doing Buffered Event count by using Count Buffered Edges.vi, what is the max buffer size allowed?

I'm currently using Count Buffered Edges.vi to do Buffered Event count with the following settings,
Source : Internal timebase, 100Khz, 10usec for each count
gate : use the function generator to send in a 50Hz signal(for testing purpose only). Period of 0.02sec
the max internal buffer size that i can allocate is only about 100~300. Whenever i change both the internal buffer size and counts to read to a higher value, this vi don't seem to function well. I need to have a buffer size of at least 2000.
1. is it possible to have a buffer size of 2000? what is the problem causing the wrong counter value?
2. also note that the size of max internal buffer varies w
ith the frequency of signal sent to the gate, why is this so? eg: buffer size get smaller as frequency decrease.
3. i'll get funny response and counter value when both the internal buffer size and counts to read are not set to the same. Why is this so? is it a must to set both value the same?
thks and best regards
lyn

Hi,
I have tried the same example, and used a 100Hz signal on the gate. I increased the buffer size to 2000 and I did not get any errors. The buffer size does not get smaller when increasing the frequency of the gate signal; simply, the number of counts gets smaller when the gate frequency becomes larger. The buffer size must be able to contain the number of counts you want to read, otherwise, the VI might not function correctly.
Regards,
RamziH.

What is ths maximum PDO read buffer size using the Series 2 CAN cards?

Does anyone know the maximum size for the PDO read buffer when using a Series 2 PCI NI-CAN card?

Hi
The maximum size for a single PDO does not depent on the series of your board it is depending on what else you are doing with the CANopen Library.
The board uses a specific shared memory to transfer messages between driver and hardware. The size of this memory fits nearly 350 messages.
The CANopen Config takes 100 messages for different services like NMT. That means the maximum size for a single PDO would be approx. 250 messages.
Or for 5 different PDOs 50 each. But normaly you can leave the buffer size to zero, thus the PDO Read would allways read the newest data.
This calculation is true for the board. That means you have 350 messages per board and 2 ports whould need to share the memory.
DirkW

Buffer size to what value? Digital Output

HI,
I am trying to write digital waveforms and constants on 14 bits of the port0 [see picture attached] but I always get the error of too small buffer size.
Actually I don't know what numeric value I should wire to the sample clock of the DO instead of 256.
Previously I generated digital waveforms simply autoindexing a for loop's loop index values at the loop's border and I wired this array directly to the DO write and it worked on 8 bits. At that time I put 256 as buffer size because 2^8=256.
Now the situation would be very similar, I want to output digital waveforms on 8 bits and constants on the other 6 bits. 2^14 as buffer size doesn't work. Can somebody please advise how to calculate the correct buffer size.
Thanks,
Krivan
Attachments:
buffersize.PNG ‏35 KB

Hey Krivan,
You can use a property node to edit the size of the buffer much like I have done (see attached image.). For this piece of code you should also have a 1D Boolean array in order to write to the correct channels and also ensure that the line grouping on the create task is set to on channel for each line.
Regards
Andrew George @ NI UK
Attachments:
Krivan.png ‏116 KB

What is the default buffer size if we dont specify in buffer write?

If we dont specify what is the default buffer size in BufferedWriter. How to increase/decrease the size of it?
What is the purpose of flush?
If flush() is not used, only partial content is written to the file. Is it because of the default size of the buffer.

THis is the bufferedwriter class, it helps to look at them, look at the bold underlined, thats answers your defualt buffer size
* @(#)BufferedWriter.java 1.26 03/12/19
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
package java.io;
* Write text to a character-output stream, buffering characters so as to
* provide for the efficient writing of single characters, arrays, and strings.
* The buffer size may be specified, or the default size may be accepted.
* The default is large enough for most purposes.
* A newLine() method is provided, which uses the platform's own notion of
* line separator as defined by the system property <tt>line.separator</tt>.
* Not all platforms use the newline character ('\n') to terminate lines.
* Calling this method to terminate each output line is therefore preferred to
* writing a newline character directly.
* In general, a Writer sends its output immediately to the underlying
* character or byte stream. Unless prompt output is required, it is advisable
* to wrap a BufferedWriter around any Writer whose write() operations may be
* costly, such as FileWriters and OutputStreamWriters. For example,
* <pre>
* PrintWriter out
* = new PrintWriter(new BufferedWriter(new FileWriter("foo.out")));
* </pre>
* will buffer the PrintWriter's output to the file. Without buffering, each
* invocation of a print() method would cause characters to be converted into
* bytes that would then be written immediately to the file, which can be very
* inefficient.
* @see PrintWriter
* @see FileWriter
* @see OutputStreamWriter
* @version 1.26, 03/12/19
* @author Mark Reinhold
* @since JDK1.1
public class BufferedWriter extends Writer {
private Writer out;
private char cb[];
private int nChars, nextChar;
private static int defaultCharBufferSize = 8192;
* Line separator string. This is the value of the line.separator
* property at the moment that the stream was created.
private String lineSeparator;
* Create a buffered character-output stream that uses a default-sized
* output buffer.
* @param out A Writer
*public BufferedWriter(Writer out) {*
* this(out, defaultCharBufferSize);*
* Create a new buffered character-output stream that uses an output
* buffer of the given size.
* @param out A Writer
* @param sz Output-buffer size, a positive integer
* @exception IllegalArgumentException If sz is <= 0
public BufferedWriter(Writer out, int sz) {
 super(out);
 if (sz <= 0)
 throw new IllegalArgumentException("Buffer size <= 0");
 this.out = out;
 cb = new char[sz];
 nChars = sz;
 nextChar = 0;
 lineSeparator = (String) java.security.AccessController.doPrivileged(
new sun.security.action.GetPropertyAction("line.separator"));
/** Check to make sure that the stream has not been closed */
private void ensureOpen() throws IOException {
 if (out == null)
 throw new IOException("Stream closed");
* Flush the output buffer to the underlying character stream, without
* flushing the stream itself. This method is non-private only so that it
* may be invoked by PrintStream.
void flushBuffer() throws IOException {
 synchronized (lock) {
 ensureOpen();
 if (nextChar == 0)
 return;
 out.write(cb, 0, nextChar);
 nextChar = 0;
* Write a single character.
* @exception IOException If an I/O error occurs
public void write(int c) throws IOException {
 synchronized (lock) {
 ensureOpen();
 if (nextChar >= nChars)
 flushBuffer();
 cb[nextChar++] = (char) c;
* Our own little min method, to avoid loading java.lang.Math if we've run
* out of file descriptors and we're trying to print a stack trace.
private int min(int a, int b) {
 if (a < b) return a;
 return b;
* Write a portion of an array of characters.
* Ordinarily this method stores characters from the given array into
* this stream's buffer, flushing the buffer to the underlying stream as
* needed. If the requested length is at least as large as the buffer,
* however, then this method will flush the buffer and write the characters
* directly to the underlying stream. Thus redundant
* <code>BufferedWriter</code>s will not copy data unnecessarily.
* @param cbuf A character array
* @param off Offset from which to start reading characters
* @param len Number of characters to write
* @exception IOException If an I/O error occurs
public void write(char cbuf[], int off, int len) throws IOException {
 synchronized (lock) {
 ensureOpen();
if ((off < 0) || (off > cbuf.length) || (len < 0) ||
((off + len) > cbuf.length) || ((off + len) < 0)) {
throw new IndexOutOfBoundsException();
} else if (len == 0) {
return;
 if (len >= nChars) {
 /* If the request length exceeds the size of the output buffer,
 flush the buffer and then write the data directly. In this
 way buffered streams will cascade harmlessly. */
 flushBuffer();
 out.write(cbuf, off, len);
 return;
 int b = off, t = off + len;
 while (b < t) {
 int d = min(nChars - nextChar, t - b);
 System.arraycopy(cbuf, b, cb, nextChar, d);
 b += d;
 nextChar += d;
 if (nextChar >= nChars)
 flushBuffer();
* Write a portion of a String.
* If the value of the <tt>len</tt> parameter is negative then no
* characters are written. This is contrary to the specification of this
* method in the {@linkplain java.io.Writer#write(java.lang.String,int,int)
* superclass}, which requires that an {@link IndexOutOfBoundsException} be
* thrown.
* @param s String to be written
* @param off Offset from which to start reading characters
* @param len Number of characters to be written
* @exception IOException If an I/O error occurs
public void write(String s, int off, int len) throws IOException {
 synchronized (lock) {
 ensureOpen();
 int b = off, t = off + len;
 while (b < t) {
 int d = min(nChars - nextChar, t - b);
 s.getChars(b, b + d, cb, nextChar);
 b += d;
 nextChar += d;
 if (nextChar >= nChars)
 flushBuffer();
* Write a line separator. The line separator string is defined by the
* system property <tt>line.separator</tt>, and is not necessarily a single
* newline ('\n') character.
* @exception IOException If an I/O error occurs
public void newLine() throws IOException {
 write(lineSeparator);
* Flush the stream.
* @exception IOException If an I/O error occurs
public void flush() throws IOException {
 synchronized (lock) {
 flushBuffer();
 out.flush();
* Close the stream.
* @exception IOException If an I/O error occurs
public void close() throws IOException {
 synchronized (lock) {
 if (out == null)
 return;
 flushBuffer();
 out.close();
 out = null;
 cb = null;
What Flush(); does
Example, you have a file called c, your writer is b and buffereredwriter is a. so your programs calls a, a talks to b, and b talks to c. when you call the Flush method, the information is sent to the outfile which is c immediately before you even close the file, because when you write to the file, it does not write directly, it writes to a buffer, so flush actually causes the buffer to write to file. Also if you call the close method on that file without the flush, the buffer will still get flushed.
consider BufferedWriter c = new BufferedWriter(new PrintWriter("c:\\c"));
you wrap printwriter into a buffered writer, now if you close this "connection" to the file, the buffer will get flushed, noting that all the data is sitting in the buffered and not yet in the file, and this happens if something dont break...

Sudden latency! No change of buffer size or hardware. What give?

I'm trying to record a song and there's latency. I was recording two nights ago and everything was fine. The only thing that's happened between now and then is I unplugged my gear and replugged it today. The buffer size is set to 256 (and always has been as far as I know). Is it possible that the latency is due to a faulty hardware connection? I don't understand how it could be software related. Also, if the solution is to change my buffer size (which I tried and it does reduce the latency at 32) does that affect the sound quality? I find this all quite mysterious... and infuriating.

Reducing latency does not affect soundquality, but computer performance.
Buffer 256 induces pretty much latency. On my system, RME Babyface, 14.8 ms roundtrip.
And I find it quite useless to record with. So I go for buffer 64/32, or simply mute the channel I'm recording to.
And monitoring through my interface........But you didn't explain if your problem is MIdi or audio related.
With first version of LPX (10.0) I experienced som strange behaviour, too. It seems to have gone now.

How to read messages longer than network buffer size

The logic of my application is:
the client sends a request to the server and wait, in blocking mode, for its response.
The server can responde with strings longer than 64KB (size of their sending and receiving buffer size), so under the hood, can also execs more than one socketChannel.write
Nothing in the message says where it finish, nevertheless the client needs to assemble all in one big
string.
How can the client deal with this ? I'd like keep it as simple as possible (without using a selector)
any thoughts ?
thanks in advance

Your above post suggests that it can send more than one packet (even ignoring the 64k limit.)
In that case the data of the message must contain sufficient information. If not then the solution is not determinate.
Ideally what you should received is a message and not just data. The message defines it contents. So you know how long it is and maybe even when it ends.
Alternatively the data might contain something. For example if you are recieving well formatted XML then you can create a simple parser that just looks for the end tag. If it isn't well formatted, or at least you can not rely on that then it is much harder.

Linux Serial NI-VISA - Can the buffer size be changed from 4096?

I am communicating with a serial device on Linux, using LV 7.0 and NI-VISA. About a year and a half ago I had asked customer support if it was possible to change the buffer size for serial communication. At that time I was using NI-VISA 3.0. In my program the VISA function for setting the buffer size would send back an error of 1073676424, and the buffer would always remain at 4096, no matter what value was input into the buffer size control. The answer to this problem was that the error code was just a warning, letting you know that you could not change the buffer size on a Linux machine, and 4096 bytes was the pre-set buffer size (unchangeable). According to the person who was helping me: "The reason that it doesn't work on those platforms (Linux, Solaris, Mac OSX) is that is it simply unavailable in the POSIX serial API that VISA uses on these operating systems."
Now I have upgraded to NI-VISA 3.4 and I am asking the same question. I notice that an error code is no longer sent when I input different values for the buffer size. However, in my program, the bytes returned from the device max out at 4096, no matter what value I input into the buffer size control. So, has VISA changed, and it is now possible to change the buffer size, but I am setting it up wrong? Or, have the error codes changed, but it is still not possible to change the buffer size on a Linux machine with NI-VISA?
Thanks,
Sam

The buffer size still can't be set, but it seems that we are no longer returning the warning. We'll see if we can get the warning back for the next version of VISA.
Thanks,
Josh

Where can I change the buffer size for LKM File to Oracle (EXTRENAL TABLE)?

Hi all,
I'd a problem on the buffer size the "LKM File to Oracle (EXTRENAL TABLE)" as follow:
2801 : 72000 : java.sql.SQLException: ORA-12801: error signaled in parallel query server P000
ORA-29913: error in executing ODCIEXTTABLEFETCH callout
ORA-29400: data cartridge error
KUP-04020: found record longer than buffer size supported, 524288, in D:\OraHome_1\oracledi\demo\file\PARTIAL_SHPT_FIXED_NHF.dat
Do you know where can I change the buffer size?
Remarks: The size of the file is ~2Mb.
Tao

Hi,
The behavior is explained in Bug 4304609 .
You will encounter ORA-29400 & KUP-04020 errors if the RECORDSIZE clause in the access parameters for the ORACLE_LOADER access driver is larger than 10MB and you are loading records larger than 10MB. Which means their is a another limitation on read size of a record which is termed as granule size. If the default granule size is less then RECORDSIZE it limits the size of the read buffer to granule size.
Use the pxxtgranule_size parameter to change the size of the granule to a number larger than the size specified for the read buffer.You can use below query to determine the current size of the granule.
SELECT KSPFTCTXPN PARAMETER_NUMBER,
KSPPINM PARAMETER_NAME,
KSPPITY PARAMETER_TYPE,
KSPFTCTXVL PARAMETER_VALUE,
KSPFTCTXDF IS_DEFAULT,
KSPPIFLG MODIFICATION_FLAG,
KSPFTCTXVF VALUE_FLAG
FROM X$KSPPI X, X$KSPPCV2 Y
WHERE (X.INDX+1) = KSPFTCTXPN AND
KSPPINM LIKE '%_px_xtgranule_size%';
There is no 'ideal' or recommended value for pxxtgranule_size parameter, it is safe to increase it to work around this particular problem. You can set this parameter using ALTER SESSION/SYSTEM command.
SQL> alter system set "_px_xtgranule_size"=10000;
Thanks,
Sutirtha

How do you determine ip and op buffer size on a 3550-12G

I have a Cisco 3550-12G switch and I want to check to see if the input buffers and the output buffers for port gi0/12 are the same size. Is there a simple way to do this, I tried using the show buffers command but I couldn't seem to find what I was looking for. Help!

Hi,
"The 3550 switch uses central buffering. This means that there are no fixed buffer sizes per port. However, there is a fixed number of packets on a Gigabit port that can be queued. This fixed number is 4096. By default, each queue in a Gigabit port can have up to 1024 packets, regardless of the packet size."
http://www.cisco.com/warp/public/473/187.html#topic7
HTH,
Bobby
*Please rate helpful posts.

What is the max size of a zip file with the JDK1.5 ?

Hello everybody,
I'm a french student and for a project, I need to create a zip file, but I don't know in advance the number and the size of files to include in my zip.
I wish to know if someone have the answer to my question : what is the max size of a zip file with the JDK1.5 ? I believe that with the JDK1.3, the limit size of a zip was about 2Go, wasn't ?
Thank you for all answer !
Good day !
PS : sorry for my very poor english ;-)

Here is all I have found for the moment :
...Okay, what about my suggestion of creating your own 10GB file?
Try this:import java.io.File;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.util.Random;
class Main {
 public static void main(String[] args) {
 long start = System.currentTimeMillis();
 int mbs = 1024;
 writeFile("E:/Temp/data/1GB.dat", mbs);
 long end = System.currentTimeMillis();
 System.out.println("Done writing "+mbs+" MB's to disk in "+
 ((end-start)/1000)+" seconds.");
 private static void writeFile(String fileName, int numMegaBytes) {
 try {
 int numBytes = numMegaBytes*1024*1024;
 File file = new File(fileName);
 FileChannel rwChannel =
 new RandomAccessFile(file, "rw").getChannel();
 ByteBuffer buffer = rwChannel.map(
 FileChannel.MapMode.READ_WRITE, 0, numBytes);
 Random rand = new Random();
 for(int i = 1; i <= numMegaBytes; i++) {
 for(int j = 1; j <= 1024; j++) {
 byte[] bytes = new byte[1024];
 rand.nextBytes(bytes);
 buffer.put(bytes);
 rwChannel.close();
 } catch(Exception e) {
 e.printStackTrace();
}On my machine it took me 43 seconds to create a 1GB file, so it shouldn't take too long to create your own 10GB. Then try zipping that file.
Good luck.

What Is Ideal Buffer Size?

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