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Backblaze does use RAID (erasure coding): data is striped across 20 drives, with 17 needed to complete a read. See: https://www.backblaze.com/b2/storage-pod.ht
by prirun 7y ago
Backblaze does use RAID (erasure coding): data is striped across 20 drives, with 17 needed to complete a read. See:
https://www.backblaze.com/b2/storage-pod.html https://www.backblaze.com/b2/storage-pod.html
"For Backblaze Vault Storage Pods each is one of 20 pods needed to create a Backblaze Vault. A Backblaze Vault divides up a file into 20 pieces (17 data and 3 parity) and places a piece of the file on each of the 20 Storage Pods in the Vault. We use our own implementation of Reed-Solomon to encode and distribute the files across the 20 pods, achieving 99.99999% data durability. We open-sourced our Reed-Solomon encoding implementation as well."
- labawi 7y agoThey 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/