I've been wanting to backup my server to a more reliable format than hard drives for a while now, so I was looking at optical storage. I'd always considered Blu-rays way too expensive, and hadn't bothered doing the maths until today, but I thought seeing as I was doing the calculations I might as well put them up here in case anyone's interested. Hopefully it's useful to someone
Assuming I want to backup 3TB of data, here are my current options from Verbatim @ Amazon.co.uk (roughly):
650 DVDs @ £21 for a 100 pack - £140 - 5p/gig
360 DL-DVDs @ £25 for a 25 pack - £360 - 12p/gig
120 25GB BD-Rs @ £110 for a 25 pack - £520 - 17p/gig
60 50GB BD-Rs @ £220 for a 25 pack - £520 - 17p/gig
Or
2 HD154UIs @ £75 each - £150 - 5p/gig
19 Intel 160GB SSDs @ £340 each - £6460 - £2.15/gig
So effectively, as things stand, DVDs are roughly neck and neck with mechanical hard drives - although there's no way you'd catch me taking 650 DVDs as a preference to two hard drives. Equally though, there's no way you'd get me burning 360 dual-layer DVDs, so I think the only sensible route would be the blu-rays. In that situation, there's no difference between 25GB and 50GB when it comes to price per gig, so you'd obviously take the 50GB option in this situation. Maybe if it dropped to about £200 I'd consider it a possible buy... for files that need to be archived long term, it's a lot less hassle putting them on a disk and spindling it - as opposed to syncing and so on with hard drives. I imagine it will be a fairly long time before BDs drop to DVD pricing (per gig) though.