I did a quick bit of math, considering replacing my current latest Gluster brick with RaspberryPi bricks. I’m taking 125€ a disk for the HDs, as the actual price doesnt matter that much here. I’m also using the same price for both options, while the Rasp-pi needs USB disks and those will at least cost more or even not be available in the biggest sizes. But let’s ignore that for a second. Let’s also ignore the performance reports I found on Google +.
The Current: A mini ITX brick with 4 HDs in soft Raid 4 on Debian.
- 4 disks (€500), 3 actual storage disks, 1 loss
- Mini-ITX hardware, c2-rack-v3 (€400, this is an honest estimate)
- Totalling €900
Compared to the Pi solution, and here the numbers generally go up..
1 disk with redundancy would mean
- 2 disks (€250), 1 actual storage disk, 1 loss
- Ras-Pi hardware, 30€ a box, 1 box a disk (€60)
- Totalling €310 for a 2 disk solution
Which looks really nice, but because the big cost is actualy in the disks, keeping their number down is the most important to keep the price down. Keeping that in mind and doing the math for a storage cluster parallelling the mini-ITX brick, we get the following. Considering replication over 2 disks, then putting those together to make a big storage volume. ie Raid 1+0 with 6 disks.
- 6 disks (€750); 3 actual storage disks, 2 lost disks
- Ras-Pi hardware; 30 a box, 1 a disk (€180)
- Totalling €930
so, more expensive, not to mention the mess of boxes and harddisks and network cables and the switch to connect them all, …. One could consider USB hubs and multiple disks a Pi, but that would not make a considerable difference in price (€90, actually making it cheaper), but would impact performance, I expect.
GlusterFS also offers striped storage, but striping is bad. (no sense in repeating the arguments, it’s all there. And I don’t use a single 100gb+ file; not even one.)
An interesting consideration, but in the end, a Pi gluster doesn’t make sense in my situation. It d be real cool though 😀
As an aside, I have similar considerations when it comes to growing the cluster with new Mini-ITX boxes, retiring older boxes (most notably the initial 2-disk brick), .. But I will probably have to retire the 2 disk box when the 3 brick cluster gets full and will probably not expand to 4 boxes ever, with the trend in bigger disks over time and the power consumption consideration. But time will tell 🙂