Archive for the ‘Technology’ Category

So out of a sudden you notice a few LUNs are missing from one or more of your ESX servers. Strange isn’t it? So you do a storage scan / refresh and they still do not automatically appear. You look for additional LUNs to add to your ESX server but as you’re adding them you are told that they will be formatted, this is obviously not an option if you have any data in them!

To solve this problem log into your ESX4 server and become root:

$ sudo su –

Find the LUNS that have been unmounted:
# esxcfg-volume -l
Find the VMFS3 UUID/label and perform the command:
Rescan the LUNs, where XX is the number of the software iSCSI adapter, 32, 33, etc…
# esxcfg-rescan vmhbaXX
That’s it. you’re done! Your LUNs will reappear in your ESX and you can go have a beer after work with your buddies, no data lost!

A couple of my NetApp NFS volumes are being overly deduplicated, usually that’s a good thing but DFM (Data Fabric Manager) is set up out of the box to notify you if they reach the 140% and 150% marks. This is an easy fix.

To eliminate these alerts set the over deduplication thresholds to a higher value in the DFM server:

dfm options set volNearlyOverDeduplicatedThreshold=<higher value>
dfm options set volOverDeduplicatedThreshold=<higher value>

If you’re like me and have already configured your 2010 Exchange CAS in a WNLB cluster then you must have chosen 1 of 3 choices: Unicast, Multicast or IGMP Multicast. At first I went with Unicast as it was the easiest one to setup but then I realized that I may not want Unicast due to the nature of how it operates. An excerpt of a VMware white paper on MS load balancing reads:

Unicast mode works seamlessly with all routers and Layer 2 switchs. However, this mode induces switch flooding, a condition in which all switch ports are flooded with Network Load Balancing traffic, event ports to which servers not involed in Network Load Balancing are attached.

As you can see that may not be something you want to do. So I switched it up to Multicast, but once I did that I was no longer able to hit the virtual IP address associated with my CAS cluster. In order to fix this you must add a static ARP entry in the router, mapping the cluster IP address to its MAC address:

User Access Verification
Enter configuration commands, one per line.  End with CNTL/Z.

Where 10.X.X.X is the virtual IP address of my WNLB and YYYY.YYYY.YYYY is the virtual MAC address created for me by WNLB. After I completed that command I was able to connect to Exchange.

If you’ve ever removed a user off the BlackBerry Enterprise Server via the Administrator Web Console and have come to find that you’re no longer able to re-add the user this might help you:

  • Connect to the database from within the BES server (where BLACKBERRY is the name of your database instance, note it could be something else depending on your setup.)
C:\> sqlcmd -S .\BLACKBERRY
  • Dump a list of possible names:
1> use BESMgmt
2> select DisplayName from UserConfig
3> go
Changed database context to 'BESMgmt'.
Carlos Serpa
(1 rows affected)
  • Remove the desired user:
1> use BESMgmt
2> delete from UserConfig where DisplayName="Carlos Serpa"
3> go
Changed database context to 'BESMgmt'.
(1 rows affected)
  • Exit:
1> exit

After a yum update and later on a reboot I broke my Trixbox 2.8 / Nagios server as it wasn’t dialing out anymore using the FXO card attached to the server. The server dials out thanks to Asterisk performing a text2speech function which eventually results in a call to me through one of my company’s POTS. After some research and log searching I got the following errors identified:

Loading DAHDI hardware modules:
FATAL: Module dahdi not found.
wct4xxp:  FATAL: Module wct4xxp not found.       [FAILED]
wcte12xp:  FATAL: Module wcte12xp not found.     [FAILED]
wct1xxp:  FATAL: Module wct1xxp not found.       [FAILED]
wcte11xp:  FATAL: Module wcte11xp not found.     [FAILED]
wctdm24xxp:  FATAL: Module wctdm24xxp not found. [FAILED]
wcfxo:  FATAL: Module wcfxo not found.           [FAILED]
wctdm:  FATAL: Module wctdm not found.           [FAILED]
wcb4xxp:  FATAL: Module wcb4xxp not found.       [FAILED]
wctc4xxp:  FATAL: Module wctc4xxp not found.     [FAILED]
xpp_usb:  FATAL: Module xpp_usb not found.       [FAILED]
Error: missing /dev/dahdi!

The error could be duplicated by trying to start the dahdi service (# service dahdi start) or by simply restarting the server and looking at server load up.

Researching the forums showed that Trixbox 2.8 now uses dahdi modules instead of zap modules but I had the dahdi modules and packages installed, which led me to see what kernel I was actually running, it seemed I was actually running a XEN kernel, 2.6.18-164.11.1.el5xen to be exact, a-ha!

I am unsure why I had installed XEN kernels but it must have been a mistake and 2.6.18-164.11.1.el5xen was set up as my default kernel boot option. I uninstalled kernels, rebooted, ran setup-pstn and it’s all back to normal!

[root@hostname][~]# cat /etc/grub.conf
# grub.conf generated by anaconda
# Note that you do not have to rerun grub after making changes to this file
# NOTICE:  You have a /boot partition.  This means that
#          all kernel and initrd paths are relative to /boot/, eg.
#          root (hd0,0)
#          kernel /vmlinuz-version ro root=/dev/sda2
#          initrd /initrd-version.img
title CentOS (2.6.18-164.11.1.el5)
        root (hd0,0)
        kernel /vmlinuz-2.6.18-164.11.1.el5 ro root=LABEL=/
        initrd /initrd-2.6.18-164.11.1.el5.img
title trixbox-base (2.6.18-128.1.10.el5)
        root (hd0,0)
        kernel /vmlinuz-2.6.18-128.1.10.el5 ro root=LABEL=/
        initrd /initrd-2.6.18-128.1.10.el5.img
[root@hostname][~]# dahdi_cfg -vv
DAHDI Tools Version - 2.2.1
DAHDI Version: 2.2.1
Echo Canceller(s): MG2
Channel map:
Channel 01: FXS Kewlstart (Default) (Echo Canceler: mg2) (Slaves: 01)
1 channels to configure.
Setting echocan for channel 1 to mg2
[root@hostname][~]# /etc/init.d/dahdi restart
Unloading DAHDI hardware modules: ERROR: Module dahdi_echocan_mg2 is in use
ERROR: Module wcfxo is in use
ERROR: Module dahdi is in use by dahdi_echocan_mg2,wcfxo
Loading DAHDI hardware modules:
  wct4xxp:                                                 [  OK  ]
  wcte12xp:                                                [  OK  ]
  wct1xxp:                                                 [  OK  ]
  wcte11xp:                                                [  OK  ]
  wctdm24xxp:                                              [  OK  ]
  wcfxo:                                                   [  OK  ]
  wctdm:                                                   [  OK  ]
  wcb4xxp:                                                 [  OK  ]
  wctc4xxp:                                                [  OK  ]
  xpp_usb:                                                 [  OK  ]
Running dahdi_cfg:                                         [  OK  ]