geekomatic

BufferedInputStream's Default Buffer Size Compared to Hard Disk Size

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We can see that Java's BufferedInputStream (BIS) default buffer size has grown over time. I thought it would be interesting to compare it against other metrics in Computer Science, the most famous of which is Moore's Law, which I compared with BIS in my last post. This time around, I have the data points from describing the capacity of hard disks sold during the years since Java's debut.

(Larger Image)

In the next post I'll be comparing BIS's default buffer size with the speed of serial buses (which are commonly used to interface a disc drive to the CPU and memory) over time.

BufferedInputStream Default Buffer Size Series: Previous | Next

BufferedInputStream's Default Buffer Size Compared to Moore's Law

BufferedInputStream Default Buffer Size Series: Previous | Next

Moore's law describes a long-term trend in the history of computing hardware, in which the number of transistors that can be placed inexpensively on an integrated circuit has doubled approximately every two years.

So, taking the data points from general purpose CPUs released during the years since Java's debut, I composed the below graph.

(Larger Image)

In the next post I'll be comparing BIS's default buffer size with the size of hard disks over time.

BufferedInputStream Default Buffer Size Series: Previous | Next

ASCII Art Text for Remote Server Login Greeting

Every time I log into "my babies", I'm greeted by some ASCII art text. It serves two purposes:

Let's me know which server I am on, very visibly
Creates a sense of pride and ownership, having a flamboyent login

This is what it looks like:

To accomplish this masterpiece of engineering, I simply went to the Text Ascii Art Generator from patorjk.com, generated my desired text, pasted that into a file called .name. Next, it was just a simple edit of the .bashrc file in the home directory and have it spew out the contents of a file named where the ASCII art lives.

   cat .name

Ta da!

BufferedInputStream's Default Buffer Size Over Time

While micro-benchmarking the performance of BufferedInputStream with various buffer sizes (both on my new fast SSD and a slow slow USB-attached HDD), the question came to mind "Has this default buffer size value changed over time in Java? And if so, who decides this? And where exactly is the line between a version of Java and a JVM."

My first instinct was to ask the boffins & peasants over at Stack Overflow: Where is exactly is the demarkation between a version of Java and the JVM? While some folks answered my main question, and one SOpedian (Joachim Sauer) went on to loosely answer my real questions, there was still not an absolute answer.

Time to take a trip down history lane via teh Google, and Sun's Java archive site.

Version	Source	Reference	Year	Bytes
JDK 1.0	API Documentation	JavaDoc	1996	512
JDK 1.1	Core API Spec	JavaDoc	1997	512
JDK 1.2	Sun JDK 1.2	Source Code	1998	2048
JDK 1.3	Sun JDK1.3	Source Code	2000	2048
JDK 1.4	Java 5 bug report	bugs.sun.com	2002	2048
Java 5	JDK 5 Source	Source code	2004	8192
Java 6	Open JDK 6	Source code	2006	8192
Java 7	Open JDK7 Beta	Source code	2010	8192

So, how does that look in a graph?

Interesting. In following posts next month, I'll compare the default buffer size of BufferedInputStream with other seemingly relevant metrics, such as Moore's Law, storage bus speeds, and hard disk size over the years.

There are other Java implementations out there, and they have their own default buffer size. I'll keep this list up to date as I learn of new JVMs.

Version	Source	Reference	Bytes
win32 IBM 1.4.2 JRE	McDowell on Stack Overflow	SO Answer	2048
IcedTea6 1.4.1 (Java 6)	Max A. on Stack Overflow	SO Answer	8192

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3TB of Time Machine Backup Storage for the xtendx Office

At xtendx we are big on simple, effective, and most things Apple. With an office of only a few people, we don't have the need or desire for a dedicated "IT Guy" and so those responsibilities generally fall on me.

Most of us are on MacBook Pros and have been handeling our backups individually at home when convenient. Recently, my colleague Mattia also started using a MBP, and a critical mass of support developed for bringing our backups "in house". To that end, we ordered three 1TB LaCie Grand USB-attached external hard drives (designed by Neil Poulton.) At SFr120 each (approximately US$122) from Digitec they were a fair price.

The original plan was to connect all three drives to the Apple AirPort Extreme base station and have each Mac's Time Machine backup over the network. No go. Constant errors like "Error 17 creating backup disk image" and "Error: (-8062) SrcErr:NO CopyingTime", Machine/System Preferences becoming unresponsive, and other drama. Big Apple #fail.

After three hours of tinkering and following many suggestions found on the Intertubes (downgrading the AirPort firm ware to 7.5.1, reformatting to a non-journel file system, and renaming the drives to conform to 8.3 naming convention), I gave up. The three disks now site near our desks and are attached directly via USB. Not as nifty, but it works and my time is valuable.

I like the blinking lights.

Here are some of the logs. Maybe if someone out there on the Interwebs has a suggestion then I'll try agin.

Starting standard backup
Attempting to mount network destination using URL: 
afp://xtendx@xtendx%20AirPort%20Extreme._afpovertcp._tcp.local/Stu's%20Time%20Machine
Mounted network destination using URL: 
afp://xtendx@xtendx%20AirPort%20Extreme._afpovertcp._tcp.local/Stu's%20Time%20Machine
Creating disk image /Volumes/Stu's Time Machine-1/Stu Thompson’s MacBook Pro.sparsebundle
Disk image /Volumes/Stu's Time Machine-1/Stu Thompson’s MacBook Pro.sparsebundle mounted 
at: /Volumes/Time Machine Backups
Backing up to: /Volumes/Time Machine Backups/Backups.backupdb
Ownership is disabled on the backup destination volume.  Enabling.
Backup content size: 129.6 GB excluded items size: 12.0 GB for volume Manoa SSD
No pre-backup thinning needed: 141.11 GB requested (including padding), 926.89 GB available
Waiting for index to be ready (101)
Error writing to backup log.  NSFileHandleOperationException:*** -[NSConcreteFileHandle 
writeData:]: Input/output error
Error: (-36) SrcErr:NO Copying /Applications/Stargate.Universe.S01E10.720p.HDTV.x264-SiTV.mkv 
to /Volumes/Time Machine Backups/Backups.backupdb/Stu Thompson’s MacBook 
Pro/2010-01-18-132728.inProgress/8289BDA1-B63B-4F3C-9277-936B11355DA5/Manoa SSD/Applications
Stopping backup.
Error writing to backup log.  NSFileHandleOperationException:*** -[NSConcreteFileHandle 
writeData:]: Input/output error
Error: (-8062) SrcErr:NO Copying /Applications/Stargate.Universe.S01E10.720p.HDTV.x264-SiTV.mkv 
to /Volumes/Time Machine Backups/Backups.backupdb/Stu Thompson’s MacBook 
Pro/2010-01-18-132728.inProgress/8289BDA1-B63B-4F3C-9277-936B11355DA5/Manoa SSD/Applications
Stopping backupd to allow ejection of backup destination disk!
Error writing to backup log.  NSFileHandleOperationException:*** -[NSConcreteFileHandle 
writeData:]: Input/output error
Error writing to backup log.  NSFileHandleOperationException:*** -[NSConcreteFileHandle 
writeData:]: Input/output error
Copied 16560 files (6.1 GB) from volume Manoa SSD.
Error writing to backup log.  NSFileHandleOperationException:*** -[NSConcreteFileHandle 
writeData:]: Input/output error
Copy stage failed with error:11