Backblaze has released details around their newest v4 storage pod. This new version (finally) changes out the previous port multiplier design. Instead Backblaze uses new controllers to make the storage pods have fewer points of failure. We decided to dissect the new build and discuss changes made in this fourth major iteration.
Backblaze has changed from a few SATA cards with port multipliers to two big HighPoint Rocket 750 SATA cards. These cards have 10x SFF-8087 ports so each card can theoretically handle 40 drives each. The HighPoint cards are powered by Marvell 88SE9485 chips and are fairly hard to find. Since Backblaze sent me a preview of their article, Amazon is the only etailer with the cards in stock for just under $700 each. Marvell SATA chips do have an interesting reputation in the forums in terms of reliability across OSes, but Backblaze has used them in the past with success in their environment.
The HighPoint controllers are now directly connected to drives. The connectors now provide data and power to individual drives via what appears to be 45x SFF-8482 connectors. This change means that Backblaze can get much more performance than it could in its previous design and the company notes RAID rebuild times have dropped by days. That has a major impact on MTTDL as can be seen with the STH RAID Reliability Calculator (MTTDL model.)
One other major change is that is format could fairly easily be adapted to work with SAS drives.
Another major change is that Backblaze has moved to a single power supply design. One can see the changes below but the storage pod now includes even fewer parts because of this. The previous dual power supply design was just to feed the power requirements of drives and system. Backblaze does not utilize redundant power supply designs.
Overall this is a great change. The HighPoint controllers are a novel solution but the general scarcity of the controller likely means that we will see a different solution in a newer generation. Of course, HighPoint may decide to start producing cards in quantity again in which case that may be an issue.
One implication of the new design is that it is now nearline SAS friendly. One could certainly see this as getting much closer to a Sun Thumper competitor simply by changing the disk controllers and possibly using a SAS expander.
The final major thought on the new build is that Highpoint is still using an inexpensive Intel Core i3-2100. Newer generation Core i3 processors have AES-NI support so if Backblaze decides it was to do AES 256 encryption using hardware acceleration, a new chip would be in order. [ed.] A final BOM showed that they are using a newer Core i3 so this point is moot. Thanks Ken for catching the fact I was working from a pre-production BOM.
You can read more about the Backblaze Storage Pod V4 here.