4 ms·
They do not use RAID. They use userspace erasure coding of data stored in files on plain ext4 IIRC. Maybe they use RAID for the OS.
by labawi 7y ago
They do not use RAID. They use userspace erasure coding of data stored in files on plain ext4 IIRC.
Maybe they use RAID for the OS.
- jandrese 7y agoIt's software RAID. RAID isn't a piece of hardware, it's a system design.
- labawi 7y agoYes it is a system design. Backblaze's main reliability system is erasure coding[4] of shards of files, which is not RAID[1][2]. RAID mirrors disks or volumes on block or filesystem layers, not files in userspace. That being said, I stand corrected in that they did use RAID at some point in time[3] (RAID6 on 13+2 drives), and may still be using some form of RAID. OTOH their reliability calculations don't seem to consider RAID - calculating with individual drive failures and shard rebuilds. [1] https://en.wikipedia.org/wiki/RAID https://en.wikipedia.org/wiki/RAID [2] https://en.wikipedia.org/wiki/Non-RAID_drive_architectures https://en.wikipedia.org/wiki/Non-RAID_drive_architectures [3] https://www.backblaze.com/b2/storage-pod.html https://www.backblaze.com/b2/storage-pod.html [4] https://www.backblaze.com/blog/cloud-storage-durability/ https://www.backblaze.com/blog/cloud-storage-durability/