It's been a very long time.. always is. The hard part for this kind of blog is you only get to write when something interesting pops up or an error was encountered [and you get to solve it - right] or a new experience.
Well, I never really had the time to internalize this software when I was working with it some few months ago, in my previous job. Just last week [not true anymore; the time here is relative to when I was preparing for a interview - published December 28, 2008 @ 16:19.xx], our paths has crossed, again.
The sudden interest rose from a technical panel [or panel technical?] interview that I've been through. Well, I was satisfied with the result for at least I was able to address all the issues that they've thrown at me, 3 of them. You can't help it but even though I was advised that it has something to do with Veritas NetBackup [NBU], it always will cross with UNIX or Linux. Surprisingly, including myself, I have at least a deeper basic understanding of how NBU works than ever before [and I hope that this is right].
Please note that this so-called tutorial is more aimed to those who have worked with or working with NetBackup yet do not understand how it works. And another thing is, this is on how I understand how it works, which is not necessarily true. But so far, no one questions it, so it must be true. Before it'll cause you giddiness, let's proceed...
****** START ******
In order for a successful backup to run, in NBU environment, we need to complete The Triangle - Master, Media Manager, and Client - well on its simple state. 'Though we also have another entity such as Enterprise Media Manager or EMM server, this can be integrated into the Master, depending on your infra if it needs it to [I'm not going through definition of these so please do your part and read on other articles ;)].
Basically, all the schedules [and catalogs - valid images of a client, archiving, and restorations] are stored in the Master server. If I'm not mistaken, this is being handled by nbpem daemon which checks for backup due to all clients or makes a list for each policy that are due to run and submits it to nbjm. nbjm in turn, gets the necessary resource by coordinating with nbrb to start the backup. nbrb is responsible for allocation of resource to a job with the help of nbemm - holds the info about media and device configurations. Daemons discussed belongs to what we call Intelligent Resource Manager (IRM - resides in Master) who's working together with EMM to schedule and allocate resources for the job.
There are other daemons but I'll not go through each discussing each, however, here are some [take note of the version of your NBU, there might be some daemons that were replaced, so check out the docs]:
Master: bpcd, bpcompatd, bpdbm, ltid, nbnos, nbrd, nbsl, nbsvcmon, vmd, and pbx_exchange
Media Manager: bpcd, bpcompatd, ltid, nbnos, nbsl, nbsvcmon, vmd, pbx_exchange
Client: bpcd
Note that bpcd is the only daemon that runs on Client.
Check using:
$ netstat -an | grep -i bpcd
tcp 0 0 *.bpcd *.* LISTEN
Next up: IRM tells the Media Manager [handles the robot/tape silo] or MM to assign drive and gather data from the Client. So MM, requests the Client for the image of backup, which generates it, and sends back. Media Manager tells the Robotic Control [Robot Tape Library/Silo - I'm not sure it they're a single entity] to find a tape and mount it, afterwhich, MM sends the data to the tape.
****** END ******
That is the general picture of how backup is iniated and done. Again, I'd like to raise that these are my understanding, and I'm doing [when time permits] other reading and may modify this from time to time to correct info. But I always welcome comments: corrections, etc. which will benefit - hopefully - us all.
Note: This is not all my idea. I've read from other articles but forgot the url but thanks to whoever wrote and provided me such materials.
