Holiday Wrap-Up

 Architecture, Backup theory, General Technology, General thoughts, NetWorker  3 Responses »
Dec 232010
 

The holiday season is upon many of us – whether you celebrate xmas or christmas, or just the new year according to the Julian calendar, we’re approaching that point where things start to ease off for a lot of people and we spend more time with our families and friends.

Before I wrap up for the year, I wanted to spend a few minutes reintroducing some of the most popular topics of the year on the blog – the top ten articles based on directly linked accesses. Going in reverse order, they are:

  • Number 10 – “Why I’d choose NetWorker over NetBackup every time“. I was basically called an idiot by someone in the storage community for writing this, but the fact remains for me that any backup product that fails to support backup dependencies is not one that I would personally choose. Given that a top search that leads people to the blog is of the kind, “netbackup vs networker” or “networker vs netbackup”, clearly people are out there comparing the two products, and I stand by my support of the primacy of backup dependency tracking.
  • Number 9 – “A tale of 4 vendors“. A couple of months ago I attended SNIA’s first Australian storage blogger event, touring EMC, IBM, HDS and NetApp. Initially I’d planned to blog a fairly literal dump of the information I jotted down during the event, but I realised instead I was more drawn to the total solution stories being told by the 4 vendors.
  • Number 8 – “NetWorker 7.5.2 – What’s it got?“. NetWorker 7.5 represented a big upgrade mark for a lot of sites, particularly those that wanted to jump the v7.3 and v7.4 release trees. I still get a lot of searches coming to the blog based on NetWorker 7.5 features and upgrades.
  • Number 7 – “Using NetWorker Client with Opensolaris“. This was written by guest blogger Ronny Egner, and has seen more interest over the last few months as Oracle’s acquisition continues to grind down paid Sun customers. If you’re interested in writing guest blog pieces for the NetWorker Blog in 2011, let me know!
  • Number 6 – “Basics – Fixing ‘NSR peer information’ errors“. I’ve said it before, and I’ll say it again: there is no valid reason why the resolution for this hasn’t been built into NMC!
  • Number 5 – “NetWorker and linuxvtl, Redux“. The open source LinuxVTL project continues to grow and develop. While it’s not suited for production environments, LinuxVTL is certainly a handy VTL to plug into a NetWorker/Linux system for testing purposes. I know – I use it almost every single day.
  • Number 4 and Number 3 – “NetWorker 7.6 SP1“. Interest in NetWorker 7.6 SP1 has been huge, and I had two blog postings about it – a preview posting based on publicly shared information from EMC, and the actual post-release article that covered some key features more in-depth.
  • Number 2 – “Carry a Jukebox with you (if you’re using Linux)“. The first article I wrote about the LinuxVTL project.
  • Number 1 – “micromanual: NetWorker Power User Guide to nsradmin“. The Power User guide to nsradmin has been downloaded well over a thousand times. I’ve been a fan of nsradmin ever since I started using NetWorker and had to administer a few NetWorker servers over extremely slow links (think dial-up speeds). It’s been very gratifying to be able to introduce so many people to such a useful and powerful tool.

Personally this year has been a pretty big one for me. Probably the biggest single event was that my partner and I made the decision to move from central coast NSW to Melbourne, Victoria during the year. We haven’t moved yet; it’s due for June 2011, but it’s going to necessitate a lot of action and work on our part to get there. It’ll be well worth the effort though, and I’ve already reached that odd point where I no longer think of the place I’m living as “home”. The reasons that led us to that decision are covered on my personal blog here. Continuing the personal front, I was extremely pleased to be able to say goodbye to the mobile “netwont” that is Vodafone in Australia. I’ve been using my personal blog to talk about a lot of varied topics running from internet censorship to invasive information requests to more mundane things, such as what makes a good consultant.

Technically I think the coming few years are going to be fascinating. Deduplication has only just started to make a splash; I think it’ll be a while before it becomes as pervasive as say, plain old disk backup, but it will have a continued and growing effect in the enterprise backup market. I predict that another bevy of dopey analysts will insist that tape is dead, just like they have every year for the last 2 decades, and at the end of the year I predict the majority of companies they interface with will still be using tape in some form or another. However, the use of tape will continue to evolve in the marketplace; as nearline disk storage becomes more regular and cheaper for backup solutions, we’ll see tape continue to be pushed out to longer term retention systems and safety nets – i.e., tape is certainly sliding away from being the primary source for recoveries in an enterprise backup environment.

One last thing – I want to thank the readers of this blog. To those people who subscribe to the mailing list, and those who subscribe to the RSS feed, to those who have the site bookmarked and to those who just randomly stumble across the site – I hope in each case you’re finding something useful, and I’m grateful for your readership.

Happy holidays to those of you celebrating or relaxing over the coming weeks, and peaceful times to those working through.

 Posted by Preston de Guise at 12:47  Tagged with: , , , , , , , , , , , , , , , , , , , , , , ,

The Half-Life of a Backup

 Architecture, Backup theory  No Responses »
Jul 142010
 

Every backup you do has a half-life, which isn’t the retention period of the backup. Now, if you’re new to NetWorker, don’t go looking for a half life setting for clients or savesets or groups; I’m referring to a concept here rather than a literal configuration option.

In most environments (in environments where the backup system is not being used for archive or HSM), a backup is most likely to be used within a short period of it being generated. That highest-probability period of usage is what I would suggest should be considered the half-life of the backup. Like regular notions of half-life, it’s not just a one-off measurement, but one that can be continued to applied throughout the lifespan of the backup.

I.e., through each successive half-life iteration, the likelihood of the backup being recalled for recovery halves again. Unlike regular half-life considerations though, the potency – or the importance – of the backup remains the same regardless of its half-life state. That is, a backup you don’t recover from until nearly the end of its life is still likely to be just as important as a backup you recover from 30 minutes after it was completed.

In normal circumstances though, what the half-life of a backup affects is the urgency of a recovery request for that backup. This, in turn, reflects the way in which your backup environment needs to facilitate recoveries. As the half-life of the backup continues to decrease, you can typically take longer to perform the recovery, but at the other end of the spectrum when the backup is quick, a recovery request will similarly expect a rapid response.

You effectively design the backup system to suit the half-life of your backups. If your backups are most likely to be used for recovery within the first two weeks of their generation, then you need to ensure that those backups are your fastest to recover from. From an architecture point of view, this would typically mean storage decisions such as ensuring that at least 2 weeks worth of backups are on disk – either as VTL backups or ADV_FILE type backups. Over time you can move backups out to slower media – making room for new, incoming backups, and keeping old backups recoverable at an appropriate level of cost effectiveness for the likely urgency of a recovery request.

For the most part, we’d normally only need to consider 4 levels of half-life for backups before we hit a level of such diminishing urgency that it becomes a bit like the high availability problem (i.e., the jump from 99.99% availability to 99.999% availability is a far more expensive proposition than the jump from 99.9% availability to 99.99% availability, etc).

These levels would be:

  • Online – For backups that have the highest recovery priority, you’ll likely use a combination of backup and snapshot software. Your “online” backups are snapshots that can be instantly retrieved from.
  • Nearline – For backups that have been recently done, you’ll want to keep them almost-immediately accessible; in a disk backup realm this means within a VTL or on ADV_FILE – in a tape only realm you’d be ensuring these are still within your tape library.
  • Offline – For backups that were done “a while ago”, you’ll want to keep them locally available for recovery purposes but not necessarily hogging more expensive backup space. In a backup to disk/VTL environment, this would either mean staging to physical tape and keeping within a tape library, or keeping on-site in a media vault. For a tape-only environment, it refers to keeping the media on-site in the media vault.
  • Offsite – For backups that have been done “some time ago”, they can typically be kept off-site with a records retention company, or in disaster recovery storage, etc.

(Note that in all of this I’m not talking about clones – copies of your backups – you need them regardless of the half-life of your backup, so I’m taking them as a given at each stage of the process. For obvious reasons, clones and originals should never be in the same location except when they’re being purged.)

There’s another way we talk about half-lives in backups – RTO (recovery time objective) and RPO (recovery point objective). However, RTO and RPO frequently intimidates business. If you’re struggling to get the business to focus on RTOs and RPOs, start with the more readily understandable term of backup half-life and see how you go.

 Posted by Preston de Guise at 08:05  Tagged with: , , , , , , , ,
© 2012 The NetWorker Blog Suffusion theme by Sayontan Sinha