Ext3 commits writes to disk within approximately 5 seconds - Ext4 can take from 40-150 seconds. In addition, if a system is using Ext3 and crashes before the commit takes place you will still have the previous contents of a file where under Ext4 the file will be empty. Theodore Tso feels that this is a failure at the application level and that the file system is behaving as designed and as specified by the POSIX spec (which apparently does not specify what is supposed to happen when a system is not shut down cleanly). His solution to the issue is to suggest proper use of fsync() and lists various scenarios/examples in post 54 of the bug report (linked above). In addition he wrote a patch that recognize the rename() situation mentioned in his post 54 yet retains the normal Ext4 behaviors and performance in the majority of cases. Also a more "proper" solution has been provided which allows the behavior of Ext3 to be retained under Ext4 by mounting it with alloc_on_commit.
A somewhat related topic is the use of on-board caching by hard drives. This behavior can be modified on most drives by using hdparm.
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Recital 10 Express Edition Linux x86 Free Download.
Recital 10 introduces the free single-user developer edition called Recital Express that can be used to develop and test multi-user Recital, Recital Server and Recital Web applications. Once the applications are ready for deployment a commercial license must be purchased. Recital Express, Recital Server Express and Recital Web Express can be used unlicensed for non-commercial purposes only.What does this download include:
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Recital 10 A powerful scripting language with an embedded database used for developing desktop database applications on Linux and Unix. Recital has a high degree of compatibility with Microsoft FoxPRO enhanced with many additional enterprise class extensions. |
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Recital 10 Web A server-side scripting language with an embedded database for creating web 2.0 applications. Includes plugins for apache and IIS. Coming soon! Recital Web Framework, a comprehensive OO framework built on YUI for building RIA (Rich Internet Applications) in Recital Web. |
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Recital 10 Server A cross-platform SQL database and application server which includes client drivers for ODBC, JDBC and .NET enabling Recital data to be accessed client/server from Windows, Linux and Mac. |
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Recital 10 Replication A comprehensive replication product that addresses urgent data movement and synchronization needs to help support disaster recovery and business continuity for Recital applications. |
Recital 10 Quick Start:
Graphical Installation
Note: The installation must be run as root. For systems with a hidden root account, please use ’Run as Root’.
- Download the distribution file into a temporary directory
- Check that the distribution file has the execute permission set
- Run the distribution file
- Follow the on screen instructions:
- License agreement
- Select components
- Installation directory and shortcuts
- Linking to /usr/bin
- ODBC Installation type (Recital Server / Recital Client Drivers)
- Java Virtual Machine selection (Recital Server / Recital Client Drivers)
- TomCat Installation type (Recital Server / Recital Client Drivers)
- Apache Firecat Plugin Installation (Recital Web Developer)
- Replication Service Type (Recital Replication Server)
- Install license file
Text Installation
Note: The installation must be run as root. For systems with a hidden root account, please precede commands with ’sudo’.
- Download the distribution file into a temporary directory
- Check that the distribution file has the execute permission set
- Run the distribution file
- Follow the on screen instructions:
- License agreement
- Select components
- Installation directory and shortcuts
- Linking to /usr/bin
- ODBC Installation type (Recital Server / Recital Client Drivers)
- Java Virtual Machine selection (Recital Server / Recital Client Drivers)
- TomCat Installation type (Recital Server / Recital Client Drivers)
- Apache Firecat Plugin Installation (Recital Web Developer)
- Replication Service Type (Recital Replication Server)
- Install license file
Some options of hdparm are dangerous and are generally listed as such in the man page.
Hdparm is available from SourceForge and there is even a version for Windows.
It would appear that gigabit LAN is not! In fact it often runs at the same speed as 100Mbps LAN. Let's look at why exactly.
After configuring your network you can use the ifconfig command to see what speeds the LAN is connected. Even though 1000Mbps is reported by the card, the reality is that the overall throughtput may well be ~100Mpbs. You can try copying a large file using scp to demonstrate this.
As it turns out, in order to use a gigabit LAN you need to use CAT6 cables. CAT5 and CAT5E are not good enough. End result, the ethernet cards throttle back the speed to reduce dropped packets and errors.
You can find a good article here titled Squeeze Your Gigabit NIC for Top Performance. After tuning up the TCP parameters i found that it made no dfifference. The principal reasons behind low gigabit ethernet performance can be summed up as follows.
- Need to use CAT6 cables
- Slow Disk speed
- Limitations of the PCI bus which the gigabit ethernet cards use
You can get an idea about the disk speed using the hdparm command:
Display the disk partitions and choose the main linux partition which has the / filesystem.
# fdisk -l
Then get disk cache and disk read statistics:
# hdparm -Tt /dev/sda0
On my desktop system the sata disk perfomance is a limiting factor. These were the results:
/dev/sda1:
Timing cached reads: 9984 MB in 2.00 seconds = 4996.41 MB/sec
Timing buffered disk reads: 84 MB in 3.13 seconds = 58.49 MB/sec
Well, that equates to a raw disk read speed of 58.49 * 8 = 467Mbps which is half the speed of a gigabit LAN.
So.. NAS storage with lots of memory looks to be the way to go... If you use the right cables!
We are pleased to announce the immediate availability of Recital 10.0.1.
Included in this version are:
- Improved SQL query optimizer
- *New* apache plugin for building Recital web apps on x86_64 (mod_recital64.so)
- Performance improvements in connections to Recital Server and Recital Web.
- Recital ODBC driver performance improvements and bug fixes
- Miscellaneous bug fixes
Existing Recital 10 users can download the patch file and apply it to an existing installation.
Enjoy!
SET DATADIR TO [ <directory> ]This command is used to specify a directory where database tables, memos, indexes, and dictionary files are located. When a table is being opened this directory is searched first before the current directory and the file search path to locate the table and its associated files. This allows the database tables to be relocated to a different file system without the need to change an existing application.