Sunday, September 9. 2007
Storage capacity consideration, II
I finally had to buy a 160GB notebook disk and already transferred all data from the old 60GB disk to the new one by using an IDE-to-USB converter. After having transferred the remaining data from my aging backup PC, I’ll have 52GB free space.
As that backup host dates back to 2001, has various quirks (Gentoo Linux, /usr on LVM on RAID-5 
) and isn’t really reliable anymore for data backup (the array sometimes dissolves), I’ll have to change some things, but won’t buy new hardware. I’ll replace Gentoo with Debian and arrange the three 80GB disks as a linear NRAID array. The system will take 5GB on RAID-1 over three disks, and the remaining three 75GB partitions become a linear 225GB device. This means that if one disk fails, only the data on that disk is lost. But that doesn’t matter, as I still have the things on my notebook anyway. Various personal and multimedia files will be backed up on DVD unregularly, and my photos are already getting backed up to CDs and stored out of house.
I elaborated the following strategy, mainly leering towards collecting a huge number of photos with my future DSLR camera:
- Short-term storage: Notebook. Here I’ll keep the most recent pictures only, for digital manipulation or simply for quick access.
- Mid-term storage: Backup host (without RAID), DVDs or plain external USB harddisks. Everything that’s on my notebook is also on that disks. But the disks will contain all pictures ever made. If a disk breaks, I’ll either have the data on the notebook or on the DVDs anyway. Only photos undergo the long-term storage.
- Long-term storage of photos: CDs. Only CDs are designed for long-term storage, DVDs aren’t. And to be safe from environmental influences, they are transferred to a house 160km away from here. Sure, CDs only take 700MB, but they’re cheap; for duplicating a possible 500GB disk full of photos, I’ll need 732 CDs. Gee! Maybe I should nevertheless take DVD±Rs for that, where I’ll only need 125 pieces. But they might not be readable anymore in a few years.
The reason for considering an external 500GB disk is that portable data tanks for photographers nowadays have a capacity of 40-80GB. I’ll reuse my 60GB notebook disk by placing it into a corresponding device. If I really manage to fill it on a holiday (>3000 RAWs?? Well, 210 RAWs per day on an exciting 2-week holiday possible, why not?), this already takes 88 CDs for long-term storage. That takes a lot of time to burn, and a lot of room to store. We’ll see how my photo rate of yield really changes.
Addendum: It seems that DVD-RAM is the appropriate media, as it lasts for 30 years according to Wikipedia, whereas CDs only last for a few years. I’d need 15 DVD-RAMs for a filled 60GB data tank, what is a more reasonable number.
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