Monday, August 06, 2007

DNS Master Slave config - Errors on slave

I have been getting errors like
"dumping master file: sl/tmp-XXXX5il3sQ: open: permission denied"
in my /var/log/messages

Finally found out that the named user is having permission issues on the slave server. When I pointed the named files to slaves/ everything went well.

Ex:
zone "example.net" {
type slave;
file "slaves/example.net";
masters { 192.168.1.1; };
};

Access Windows Network share in Fedora

I found out that smbmount and mount -t smbfs do not work anymore on Fedora.

But now you can use cifs (The Common Internet File System) to do the same as before

mount -t cifs //1.2.3.4/share /mnt/somedirectory

Refer to man mount.cifs for more options

Access NTFS Partitions on Fedora Core (5 and above)

This article is referenced here


Windows uses a different filesystem (NTFS) to store files. In order for Fedora to read that filesystem, you require NTFS support in your kernel. You can either recompile your kernel for NTFS read support -OR- obtain the proper kernel module.

To setup NTFS access you must (1) install NTFS support, (2) check how many partitions you have, (3) create mount points, (4) mount partitions, and (5) update fstab to mount at next boot.

1. Install NTFS Support

[user@localhost ~]$ sudo yum install fuse fuse-libs ntfs-3g ntfsprogs ntfsprogs-gnomevfs

No kernel version checking is required, so long as you are using a stock Fedora kernel.

2. Check Your Partitions

Use fdisk to list partitions. Most ATA hard drives will be /dev/hda. Drives may also show up as /dev/hdb, /dev/sda depending on your configuration.

[user@localhost ~]$ sudo /sbin/fdisk -lu /dev/hda | grep NTFS
/dev/hda1 * 63 33559784 16779861 7 HPFS/NTFS
/dev/hda2 33559785 67119569 16779892+ 7 HPFS/NTFS
/dev/hda3 67119570 100679354 16779892+ 7 HPFS/NTFS

Usually the first will be a drive "letter": C drive, next D, etc. Hence /dev/hda1 is my C:\ drive used by Windows.

3. Create Mount Points

For every partition in step 2 that you wish to access, you will need a "mount point". A mount point is just a directory. Common directories are: /media/ and /mnt/. Use whichever, but be consistent.

[user@localhost ~]$ cd /media/
[user@localhost media]$ sudo mkdir c_drive d_drive e_drive

You do not have to use these names, if you prefer to create folders such as movies, documents, or winxp, any name will work (without spaces).

4. Mount Partitions

Using NTFS-3G, we can mount the NTFS partition read-write, however it is recommended for novices as read-only. The following mounts and sets the permissions so all users can read the contents of each partition.

[user@localhost ~]$ sudo mount /dev/hda1 /media/c_drive -t ntfs-3g -r -o umask=0222
[user@localhost ~]$ sudo mount /dev/hda2 /media/d_drive -t ntfs-3g -r -o umask=0222
[user@localhost ~]$ sudo mount /dev/hda3 /media/e_drive -t ntfs-3g -r -o umask=0222

Read/Write Access: The above is for read-only access. In order to mount read/write, you must use the -rw -o umask=0000. Example:

[user@localhost ~]$ sudo mount /dev/hda1 /media/c_drive -t ntfs-3g -rw -o umask=0000

HIGHLY RECOMMENDED: Please run man mount to understand what umask= does.

5. Update /etc/fstab

Every time Fedora boots, the partitions must be mounted. To automatically mount, you must edit /etc/fstab.

Open /etc/fstab in an editor: (use nano instead of gedit if you do not have a GUI)

[user@localhost ~]$ sudo gedit /etc/fstab

Add these lines to the END of the file:

/dev/hda1   /media/c_drive     ntfs-3g    ro,defaults,umask=0222 0 0
/dev/hda2 /media/d_drive ntfs-3g ro,defaults,umask=0222 0 0
/dev/hda3 /media/e_drive ntfs-3g ro,defaults,umask=0222 0 0

Read/Write Access: The above is for read-only access. In order to mount read/write, you must use the rw,defaults,umask=0000. Example:

/dev/hda1   /media/c_drive     ntfs-3g    rw,defaults,umask=0000 0 0

Done!

NOTE: SELinux Problems

Users of SELinux will fix Fedora blocks the automounting of ntfs partitions when using NTFS-3G. This is a Fedora/SELinux bug, not NTFS-3G. Some support can be found on the NTFS-3G support page.. However for now users can mount everything when they log in by running:

[user@localhost ~]$ sudo mount -a

NOTE for FAT32 users

If you have FAT32 or FAT16 partitions, instead of ntfs-3g above you can use vfat to mount your partitions. No extra modules or downloads are required, this is built into the kernel. Just replace vfat for every place we have ntfs-3g when mounting and when editting /etc/fstab.

FAT32/FAT16 read and write is supported. If you wish to mount read/write, then use: '-rw' for Step 4. Mounting Partitions, and 'rw,defaults,umask=0000 0 0' for Step 5. Updating /etc/fstab.

Password Broken Sync between Windows 2003 and Linux using SFU after SP2

I had encountered this problem after installing SP2 on our AD (Windows 2003 server). Whenever you change the password in windows, it is not reflecting the change in the attribute "msSFU30Password" and hence the change does not reflect on the Linux systems.

I found a useful article at "http://blogs.msdn.com/sfu/archive/2007/04/27/windows-server-2003-sp2-breaks-sfu.aspx"

  1. Download and extract the hot fix on your system.
  2. Install SFU35-KB913030-X86-ENU.EXE from the extracted files.
    1. Double-click on this file and complete the installation. At the end, the installation will prompt you to reboot the server and this prompt features just the OK button. DO NOT click on it yet.
  3. Open a Command Prompt window, change to the folder where you have the SFU35-KB913030-X86-ENU.EXE file and run this -

    SFU35-KB913030-X86-ENU.exe /x
    This command extracts the files from the hot fix instead of kicking the hot fix installation.
  4. That'll again ask you a folder location where the files from this hot fix should be extracted. Type a path and click on OK.
  5. After extraction is complete, open this new path in Windows Explorer. Open the sfu35eng folder and here you can see all the files this hot fix updates.
  6. Depending upon which component is broken on your system, copy the psxss.exe, psxdll.dll and/or pswdsync.dll files after verifying the version number (it should be 8.0.1969.38) to your %systemroot%\system32 folder.

    Manual update of these drivers is needed since the wrongly replaced drivers have a version number corresponding to Windows Server 2003 R2 which is higher than that of the SFU 3.5 driver versions.
  7. Come back to the hot fix window which is still waiting for you to click on the OK button. Click on OK and let your system reboot.
  8. Everything should be fine now.

Thursday, July 05, 2007

Using tape backup in Linux (DAT40)

Installed an old tape drive (Seagate DAT40 20/40G), finally worked out a math for backing up critical data into multiple tapes. It is taking a long time for the backup to finish, so I decided to upgrade to an LTO1 drive that supports 100GB per tape uncompressed. That might solve the frequent tape changing.

For backing up and verifying the backup (similar to verify data after burning a cd-r) you can use the command
tar -cvpWlf /dev/st0 /home
Where,
c : create a new archive of /home
v : Verbose output
p : Ignore umask when extracting files i.e. preserve permissions on files
W : attempt to verify the archive after writing it
l : stay in local file system when creating an archive
f : Specify /dev/st0 as tape device (file)
/dev/st0: Tape device name.
/home : Directory to backup

I would like to use bzip2 compression prior to backing up to tape, that requires turning off compression on the tape drive itself. To get the current status of compression, run the command
tapeinfo -f /dev/st0

For setting the compression off
mt -f /dev/nst0 defcompression 0

For setting the compression on
mt -f /dev/nst0 defcompression 1