Linux ext3 filesystem: Deleting files won't free space -- at 100% disk usage

We've had our / filesystem used 100% with 0 bytes available. To free up some space, we've deleted a whole bunch of files, but df still reports there are 0 bytes available. Rebooting the system did not have any effect.

Apparently, the system starts to reserve space for system use. The tune2fs command reports current filesystem usage.

To see how much space is reserved, run

# tune2fs -l /dev/VolGroup00-LogVol00

To reset the reserved space to zero, run the following command as a root user.

# tune2fs -r 0 /dev/mapper/VolGroup00-LogVol00

By running the command above, we were able to free the space available for the linux users to use.

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Unable to restart the iscsid service

[root@server1 ~]# service iscsid restart
Stopping iSCSI daemon: iscsiadm: can not connect to iSCSI daemon (111)!
iscsiadm: initiator reported error (20 - could not connect to iscsid)
iscsiadm: Could not stop iscsid. Trying sending iscsid SIGTERM or SIGKILL signals manually


Starting iSCSI daemon:                                     [FAILED]


[root@server1 ~]# service iscsid stop
Stopping iSCSI daemon: iscsiadm: can not connect to iSCSI daemon (111)!
iscsiadm: initiator reported error (20 - could not connect to iscsid)
iscsiadm: Could not stop iscsid. Trying sending iscsid SIGTERM or SIGKILL signals manually


[root@server1 ~]# service iscsid start              [  OK  ]
Starting iSCSI daemon:                                    [FAILED]

Solution:
Adds a module to the Linux kernel
[root@server1 ~]# modprobe iscsi_tcp
[root@server1 ~]# iscsid

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Trying to umount: device is busy

You can see that the device is busy, so check out who is using it.

Syntax: fuser [options] <mount_point> | <filesystem>
Options:
-c Checks the mounted file system
-k Kills processes using the file system
-m Shows all processes using the file system
-u Displays user IDs
-v Provides verbose output

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Cannot send or receive emails using Outlook / Outlook Express

Cannot send emails:

There are several common reasons for not being able to receive emails through Outlook (Express). These reasons include such as

1. Temporary mail server problems

2. Wrong Outlook Express settings

3. Incorrect MX records of the domain.

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Apache: Preventing Directory Listing

You do not want people to be able to browse through directory listing? Server to prevent directory  contents to be listed. To fix it:
IndexIgnore *

Where as * is a wildcard that matches all files.

if you dont want images? To fix it:
IndexIgnore *.jpg *.png *.gif


And conversely, if your server is setup to prevent directory listing, but you want to list the directories by default, you could simply throw this into an htaccess file the directory you want displayed:
Options +Indexes

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403 Forbidden or No Permission to Access

This type of error is occurred due to permissions or .htaccess error.

Permissions:

The 403 Forbidden error means that your file has bad permissions. Directories and folders must be 755. Executable scripts within the cgi-bin folder must be 755. Images, media, and text files like HTML should be 755 or 644.

Hidden files (dot files):

If you see "client denied by server configuration" in your Error Logs, then this usually means bad file permissions, but could also mean that the visitor is trying to look at a hidden file, like the .htaccess file. You cannot look at that file in your browser, or any file name that starts with a dot.
e.g. http://domain.com/.htaccess will always result in a 403 error.

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Unable to send the mail from OutLook - part1

 Try Different SMTP Ports

Typically, SSL and port 465 work most of the time. If you can receive email but can't send any messages in Outlook, double-check that you're using the correct port number.

Sometimes ISPs or network providers block specific ports for security reasons. If the default settings don't work, you can try some alternate ports.

To Change Your Outlook SMTP Port Settings

1. In Microsoft Outlook 2010, click File, and then click Account Settings.
2. Select the account you want to change and click Change.
3. Click More Settings... and select the Advanced tab.
4. Next to Use the following type of encrypted connection, select SSL.
5. Next to Outgoing Server (SMTP), type 465. Click OK and click Next.
6. If those settings don't work,repeat steps 1-3 and select None for Use the following type of encrypted connection. Try these other ports for Outgoing server (SMTP): 80, 3535, 587, or 25.
7. Click OK and Next to see if the other ports will work.

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Assigning and Recover Grub Password

Assigning Grub Password
# grub-md5-crypt

Password: (enter new password)
Retype password: (repeat password)
$1$s3YiK$M3lxAbqA6JLm2FbDWnClQ0

Copy the contents of grub-md5-crypt  in file tmpfile

# grub-md5-crypt > tmpfile

View the content of tmpfile

# cat tmpfile

Add the resulting hash value to the file /etc/grub.conf

# vi /etc/grub.conf

#hiddenmenu

password --md5 $1$s3YiK$M3lxAbqA6JLm2FbDWnClQ0

:wq

Reboot the system forcefully

#reboot –f

Removing Grub Password
*Boot the System in Rescue Mode
# chroot /mnt/sysimage

# vi /boot/grub/grub.conf

Remove line from /boot/grub/grub.conf
hidden menu
password — md5 <password>
title Red Hat ——

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Recover root password

Root Password can be recovered in a  specialized troubleshooting mode (i.e. init 1)
*init 1 level provides a shell (i.e. sh) without logging in.

Procedure:
1. Restart the system
2. In the splash screen Select RedHat enterprise Linux
3. Press ‘e’ to edit
4. Select Kernel /vmlinuz-2.6.9-5.EL ro root=LABEL=/rhgb quiet
5. Press ‘e’ to edit
6. Edit Kernel /vmlinuz-2.6.9-5.EL ro root=LABEL=/rhgb quiet 1
7. Press Enter
8. Press ‘b’ to boot with the selected run level
*directly you will get shell prompt to assign the root password
9. sh-3.00#passwd root

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