Perhaps the most important thing to be learned from the Backblaze Pod design is how its creators made the their tradeoffs to achieve their design goals of low-cost, high density and large capacity. The design process is always a battle of cost, time and performance, with successful designs achieving the right balance. because Backblaze believes that other technologies don’t scale as cheaply, reliably and big, or can be managed as easily as HTTPs. HTTPS was chosen over iSCSI, NFS, SQL, Fibre Channel, etc. Formatted (useable) space is about of 87% of the 67 TB of raw hard drive capacity or about 58 TB per Pod.Īs noted earlier, all read/write is via HTTPS running in custom Backblaze application layer logic under Apache Tomcat 5.5. Then 15 1.5 TB drives are then combined into a single RAID6 volume using mdadm and finally, formatted with JFS using a 4 KB block size. To create a volume, fdisk is first used to create one partition per drive. Backblaze found that some other free open source OSes are more entry-level options into paid offerings. Debian was chosen because "it is truly free". The Pod boots 64-bit Debian 4 Linux using the JFS file system, with all access to and from the Pod via HTTPS (Figure 5).įigure 5: Backblaze Pod software architectureīackblaze went with JFS because they needed something that would support large TB volumes, run on Debian and have a good support community. They noted that with 25 MB/s throughput, 2 TB of data can be written in a day and a Pod filled within a month. But with an overall throughput of 25 MB/s, the Addionics card was still fast enough for Backblaze’s needs. I asked whether there was a performance hit from using the PCI-based card and Backblaze confirmed that the PCI-based card did yield lower performance than the PCIe cards. The port multiplier backplanes use a Silicon Image SiI3726, the SYBA cards use a SiI3132, and the Addonics card has a Silicon Image SiI3124. In Backblaze’s view, Silicon Image pioneered port multiplier technology, and Backblaze feels that their chips work best together. The card and backplane choices were limited to products using Silicon Image devices. Each of nine SATA cables connect to a Chyang Fun Industry (CFI Group) CFI-B53PM 5 Port SATA backplane. Speaking of SATA, Figure 4 shows the SATA subsystem, which is composed three two-port Syba SD-SA2PEX-2IR PCI Express SATA II controller cards and one Addonics ADSA4R5 4-Port SATA II PCI controller card. But after pondering the comparison chart in Figure 1, they decided that they could recoup the cost of designing and building their own storage pretty quickly. They first looked at commercial solutions. So they need a lot of storage, multiple petabytes (1 PB = 1,000 TB) worth, in fact. Backblaze provides "cloud" based unlimited backup for $5 per month per Mac OS or Windows computer, including multiple versions. Of course, we all realize that companies are in business to make a profit, so they aren’t going to be giving the fruits of their labor away.īut sometimes, the difference between what you can build yourself and what you have to pay for what you can buy is big enough to make you take the plunge into building your own NAS.Ĭloud backup company Backblaze had the same idea when they looked at the cost of buying "big iron" storage. Many SmallNetBuilder readers realize that the prices that companies like NETGEAR, QNAP, Synology, Thecus and others charge for their high-end "business class" NASes are significantly more than the cost of equivalent NASes that they could build themselves.
0 Comments
Leave a Reply. |