For now I will get roughly 10 LTO-6 tapes and rotate them. Compression will be used so I can get away using 2 tapes on each backup session which will be done every 2-3 days.
I highly doubt I will require more than 20 terabytes worth of backups at the middle of 2015.
I did consider NAS - but failures are silent and the heat given out by NASes makes it a deal breaker. I am using this for home use.
I have a server with roughly 12 terabytes worth of harddrives and it does give out quite a bit of heat so I was thinking a backup strategy using tapes could be worth considering since they are much more reliable, have lower power consumption (compared to filling the server with more harddrives) and offer better value (in terms of consumable cost)
You seem to know a fair bit. Have you used LTO btw? Any gotchas that made you wary of such things? Thanks!
My experience with Tape related backup is while I'm working with in a SI, designing system with include the need of a tape library, 20+ LTO-5 tapes for backing up 10+ servers using Symantec Backup S/W
With 10 tapes, you will work like a mechanic trying to switch the tapes during backup if you are using a single drive tape drive. For these much of tapes involved, I would have used a tape library. Unfortunately tape library are rack mounted and probably wouldn't be useful for your case unless you have a rack at home ?
Tapes are reliable when you store them properly like in dry cabinets or cool dry storerooms. However the bad part is what people don't normally think about, how do you know a piece of tape stored in your store room is still usable ? Bit flips ? fungal tape ? Like I say you need to take care of it nicely for it to work properly for you.
I don't know if you have tried restoring a system with a tape, it's a painful process that potentially take hours. Have you used tapes before, you need a catalogue that tell exactly which tape is required when you restore. That is provided by the backup software. You can use the Amanda if you like, but it's not going to be a easy process. So if you have worked with backup/restore operations before, perhaps you can give it a try.
I am not sure which class of NAS have you tried before ? I have a 5 bay Synology DS1511+ NAS running 24by7 for the last 2 years using RAID 6(upgraded halfway from RAID5) on an assorted set of WD RED and WD GREEN disks. With 1 single disk for backup.
Your concern on bit rot can be easily addressed using periodic disk scrubbing. It will create opportunity for the SMART in each disk to detect failing sectors and also for the RAID controller to ensure RAID consistency of the array. This is done automatically and any early detection of failing disks will be notified to you via email.
My NAS is running almost noiseless even during night time, and the power consumption of 5 disks is only 70+W(if I remember correctly).
For your case, I will recommend you get a Synology DS2413+ or equivalent for other branding. That will set you aside for SGD2K only, not a single LTO-6 tape drive that will cost you USD3K. Get 5x 3TB WD RED and form a RAID 6 array, it will give you near 9TB worth of diskspace. Get another 4x 3TB RED and form a RAID 5 across for you to perform backup from your main array to this backup array. That would be a total of 1.6K. Add together it only cost you SGD3.6K. Go get a APC UPS NAS that will cost you roughly <SGD200. You will still have 3 slots for you to play with. If you really have slots issues, get a DX1211+ expansion unit to scale up another 12 slots via Infiniband interface. That should give you sufficient headroom for 20TB or more.
The whole setup have redundancy and daily backup and data scrubbing all happening automatically without your intervention. When you store data in it, you know it is safe.
Any hard disk fail, just change, you have 2 set of redundancies and 2 layer of protection. If you are keen, just use Amazon S3 for your highly critical data. That's how I do it. Hence I have up to 3 layers of data protection.
What if the unit is down. Simplest solution is get another unit or upgrade to another NAS available. Synology is using Linux RAID (I don't suggest going for SHR), so it is just as compatible on any Linux Box. If for some reason you can't get a replacement unit and you are urgent for the data on the hard disk, just go get a linux box with sufficient SATA ports, plug them all in and assemble them manually using the Linux MDADM tool.
That's the beauty of using Synology. Can't say the same for other brands. Think about it and see if what I have suggested works for you.
