Backblaze is an all-you-can-eat backup service for $5/mo. As such, they couldn't afford expensive brand name RAID arrays, SANs, or NAS boxes, so they rolled their own.
They now have over 100,000TB of their original Storage Pods in versions 1, 2, and 3. All had 45 drives using nine 5-drive SATA port multipliers - not the most reliable design - which meant five drives barfed when a PM went down.
The new design has two HighPoint Rocket 750 cards, each delivering 40 6Gb/s SATA 3 interfaces through 10 mini-SAS ports. Much faster and less contention because each drive gets its own dedicated SATA and power port.
The Rocket 750s mount on an 8x PCIe 2.0 bus, giving a 4x performance boost over the earlier design. This enables much faster RAID syncs bringing up a new Pod and should - though Backblaze didn't speak to this - also enable faster rebuilds of replacement drives.
The direct connections remove the port multipliers, simplify the wiring and isolate connector issues - a common problem - to a single drive. Each mini-SAS cable fans out to 4 SATA connectors. Like this:
The old Pods had 2 power supplies for capacity, not redundancy, and that was expensive. The new Pod has a single high-efficiency power supply that powers everything and should be more reliable as well as cheaper. If you were using just a few Pods, you'd mirror data across a pair for availability.
There are other changes. New side rails improve cab mounting and access. Boot drives are on the rear for easier wiring and access.
5¢ a gig
But Backblaze's price for a 180TB Pod is now a record low $9305, including drives - just over 5¢ a gigabyte of raw capacity. You'll pay 6¢/GB if you buy from their supplier - 45 Drives - but they also offer optional redundant power and boot drives.
Backblaze has published the complete parts list so you can buy the chassis from 45 Drives and bolt the parts together yourself and save some more money. Its an open source design so you can even bend your own metal if you like.
The Storage Bits take
The Storage Pods are designed for Backblaze's particular need: low-cost storage for online backup. They would choke and die on a call-center transactional workload.
But as we gather more data - backups, log files, web content, video - we typically access it less. And while SSDs are great for transactional workloads, disk drives are still competitive for large sequential reads and writes and are way cheaper.
As drive prices drop - 5 and 6TB drives are starting to come on the market in volume - Storage Pod 4 costs will drop as well. If you need lots of capacity there's no lower cost solution.
Comments welcome, as always. Say, with 6TB drives that would be 270TB per Pod and a petabyte for about $50k next year. I remember when 500MB was $50k!
Read the entire Backblaze v4 blog post here.