A quick note about extracting and recreating RHEL6 or Centos6 (and their derivations) installation media components:
mv initrd.img /tmp/initrd.img.xz
xz –format=lzma initrd.img.xz –decompress
cpio -ivdum < ../initrd.img
The goal – connecting multiple Oracle ASM snapshots (same source LUNs, of course) to the same machine. The next process will demonstrate how to do it.
The following procedure was tested by me, and was found to be working. The version of the XenServer I am using in this particular case is 6.1, however, I belive that this method is generic enough so that it could work for every version of XS, assuming you're using iSCSI and LVM (aka - not NetApp, CSLG, NFS and the likes). It might act as a general guideline for fiber channel communication, but this was not tested by me, and thus - I have no idea how it will work.
In particular – Oracle UEK, which “claims” to be 2.6.39-xxx, but is actually 3.0.x with a lower version number. Several misbehaviors (or differences) of version 3 can be found. One of them is related to BackupExec. The service would not start on OEL6 with UEK kernels. The cause of it is an incorrect use of a function – getIfAddrs. Everything can be seen in this amazing post.
When using ‘disk show -v’ on a NetApp filer version 7.3.x, following replacement or addition of disk(s), you might see the above mentioned message. It is caused by incorrect disk label – of OnTap version 8, on an OnTap version 7.3.x system. The system cannot handle the incorrect label, and thus – ignores the disk.
SABnzbd is a nice tool. I just replaced my previous nzbget with it, due to its better handling of the obfuscated names in usenet groups. However, on an Atom CPU, the max download speeds did not go over ~5MB/s on a 100Mb/s link. This is rather sad, because nzbget did get the whole ~11MB/s speeds.
It is an amazing news to me. I really love XenServer. I think that Citrix were able to make a good use of Linux mechanisms for the purposes of virtualization, without abusing the OS layer (like some of the other virtualization solutions did). The file locations are decent (for example – most parts are located in /opt, which is the right place for it to be at), and in general, it always felt to me as if Citrix developers (and the original XenSource developers) had respect for the OS. I liked it, and still do.
Due to a major disk crash, I have had to use my ‘other’ computer for VPN connections. It meant that I have had to prepare it for the operation. I attempted to login to aJuniper-based SSL-VPN connection, however, I did get a message saying that my 64bit Java was inadequate. I had a link, as part of the error message to Juniper KB, to which I must link (remembering how I have had to search for possible solutions in the past).
I have been using the excellent template and scripts from this forum post, however, when the NetApp device is loaded with LUNs and volumes, the script will cause the Cacti to timeout, and during that time, consume CPU. The original cause of this problem was a workaround to some NetApp Perl API bug the original author found, which forced him to query the entire data set for each sub-query.