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When stress testing our loadbalancer, i was unable to get more than 20 reliable ssh connections. The following error would be reported.

ssh_exchange_identification: Connection closed by remote host

The resolution for this is quite simple.

Edit the /etc/ssh/sshd_config file and increase the MaxStartups. On my server i set this to 200.

Edit /etc/sysctrl.conf and add the following line:

net.core.netdev_max_backlog = 3000

Then apply this change:

# sysctl -p

 

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VMware products, such as ESX, Workstation, Server, and Fusion, come with a built-in VNC server to access guests.

This allows you to connect to the guest without having a VNC server installed in the guest - useful if a server doesn't exist for the guest or if you need access some time when a server would not work (say during the boot process). It's also good in conjunction with Headless Mode.

The VNC server is set up on a per-VM basis, and is disabled by default. To enable it, add the following lines to the .vmx:

RemoteDisplay.vnc.enabled = "TRUE" 
RemoteDisplay.vnc.port = "5901"

You can set a password with RemoteDisplay.vnc.key; details for how to calculate the obfuscated value given a plaintext password are in Compute hashed password for use with RemoteDisplay.vnc.key.

If you want more than one VM set up in this manner, make sure they have unique port numbers. To connect, use a VNC client pointing at host-ip-address:port. If you connect from a different computer, you may have to open a hole in the OS X firewall. If you use Leopard's Screen Sharing.app on the same computer as Fusion, don't use port 5900 since Screen Sharing refuses to connect to that.

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After an extended period of intense software development, we are pleased to announce the release of Recital 10 which is a milestone in our development efforts.
 
Recital 10 is comprised of major new versions of all of our products (which are all now Cluster Ready) as well as some new products, and a collection of open source technologies fully supported by ourselves to our customer base. 

The Recital 10 release notes can be found here.
  • Recital

    A powerful scripting language with an embedded database used for developing desktop database applications on Linux and Unix.

  • Recital Server

    A cross-platform SQL database and application server.

  • Recital Web

    A server-side scripting language with an embedded SQL database for creating web 2.0 web applications.

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The best way to learn Recital is to build some applications. The developers of Recital have written a book "Recital Essentials" which you can read here.
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A number of people have complained about data loss after a system crash when using Ext4.  A bug report was logged. According to multiple posts by a developer of Ext4, Theodore Tso, this is due to differences in approach to security and performance issues between the two file systems.

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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sernet.de maintain the latest Samba releases in a yum repository, allowing for an easy and painless install or upgrade of Samba on your yum based Linux distribution.

To install the latest available Samba execute the following commands at the shell:

# cd /etc/yum.repos.d
# wget http://ftp.sernet.de/pub/samba/experimental/centos/5/sernet-samba.repo
# yum install samba

To upgrade an existing Samba install:

# cd /etc/yum.repos.d
# wget http://ftp.sernet.de/pub/samba/experimental/centos/5/sernet-samba.repo
## Note: edit sernet-samba.repo and add the line "gpgcheck=false" otherwise 
## it will not install as it is not signed
# yum update samba

Note: These steps will install the very latest build available at sernet.de.
If you require a less bleeding edge version of Samba, use the "tested" repo. This can be found at the following URL: http://ftp.sernet.de/pub/samba/tested/rhel/5

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Recital is a dynamic programming language particularly suited to the development of database applications. While Recital still supports standard procedural programming, new extensions to the language give you the power and flexibility of object-oriented programming. Object-oriented design and object-oriented programming represent a change in focus from standard procedural programming. This short primer will give you a good understanding of how to program object-oriented Recital.
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A good article describing the configuration of samba for file/record locking can be found here.

Basically you must add these directives to the smb.conf file:

[data] 
oplocks = False 
level2 oplocks = False

The default oplock type is Level1. Level2 oplocks are enabled on a per-share basis in the smb.conf file. Alternately, you could disable oplocks on a per-file basis within the share: 

veto oplock files = /*.dbf/*.DBF/*.ndx/*.NDX/*.dbx/*.DBX/*.dbt/*.DBT/

You can further tune samba by following this guide.

If you specify the Common Internet File System (CIFS) when you mount the samba share then you must specify the following options
mount -t cifs {mount-point} -o username=name,pass=pass,directio
The directio option is used to not do inode data caching on files opened on this mount. This precludes mmaping files on this mount. In some cases with fast networks and little or no caching benefits on the client (e.g. when the application is doing large sequential reads bigger than page size without rereading the same data) this can provide better performance than the default behavior which caches reads (readahead) and writes (writebehind) through the local Linux client pagecache if oplock (caching token) is granted and held. Note that direct allows write operations larger than page size to be sent to the server.

If you get the following error when trying to mount the {mount-point}
Apr 22 16:57:39 bailey kernel: Status code returned 0xc000006d NT_STATUS_LOGON_FAILURE
Apr 22 16:57:39 bailey kernel:  CIFS VFS: Send error in SessSetup = -13
Apr 22 16:57:39 bailey kernel:  CIFS VFS: cifs_mount failed w/return code = -13
The you need to create the Samba user specified on the mount command
smbpasswd -a username
FYI - Make sure you umount all the Samba {mount-point(s)} before shutting down Samba.
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In Linux you can run lsof and pipe it though grep for the files you are interested in, for example;
$ lsof | grep db.exe | grep accounts
db.exe    16897      john    6uw     REG      253,0    20012    3413872 /usr/recital100/qa/accounts.dbf
db.exe    16897      john    7u      REG      253,0     4176    3413885 /usr/recital100/qa/accounts.dbx
If you want to check for locks you can use lslk, for example;
$ lslk | grep db.exe | grep accounts
db.exe    16897 253,0 3413872 20012  w 0  0  0 12319   0 /usr/recital100/qa/accounts.dbf
If you don't have lslk installed you can install it with one of the updaters, for example on redhat linux:
$ yum update lslk

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To insert code samples into your articles in joomla, you use the pre tag like this:

<pre xml:lang="xxx"> your code goes here </pre>

You can use any of the following languages for colorizing your code in articles. 
 

recital, abap, dos, lotusscript, rails, actionscript3, dot, lscript, reg, actionscript, d, lua, robots, ada, eiffel, m68k, ruby, apache, email, make, sas, applescript, fortran, matlab, scala, apt_sources, freebasic, mirc, scheme, asm, genero, mpasm, scilab, asp, gettext, mxml, sdlbasic, autoit, glsl, mysql, smalltalk, avisynth, gml, nsis, smarty, bash, gnuplot, objc, sql, basic4gl, groovy,

ocaml-brieftcl, bf, haskell, ocaml, teraterm, blitzbasic, hq9plus, oobas, text, bnf, html4strict, oracle11, thinbasic, boo, idl, oracle8, tsql, caddcl, index.html, pascal, typoscript, cadlisp, ini, perl, vbnet, cfdg, inno, per, vb, cfm, intercal, php-brief, verilog, cil, io, php, vhdl, c_mac, java5, pic16, vim, cobol, java, pixelbender, visualfoxpro, c, javascript, plsql, visualprolog, cpp, kixtart, povray, whitespace, cpp-qt, klonec, powershell, winbatch, csharp, klonecpp, progress, xml, css, latex, prolog, xorg_conf, delphi, lisp, providex, xpp, diff, lolcode, python, z80, div, lotusformulas, qbasic

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