3 ms·

I wonder how they can guarantee data integrity. Are they checksumming on a higher level and is that cheaper than using ZFS with necessarily more expensive hard

• tachion 12y ago
  I am also a bit suprised they're running Debian 4 + JFS combination instead of something a bit more modern, like FreeBSD and ZFS, for example, my default choice when it comes to filesystem nowdays. I'd love to hear abou their reasoning behind that and possible plans (if any) to move to something more recent, when it comes to software layer.
• epistasis 12y ago
  As of 2012, they checksum each file and check it every few weeks, and if a file went bad they have the backup client retransmit it: https://help.backblaze.com/entries/20926247-Security-Question-Round-up- https://help.backblaze.com/entries/20926247-Security-Questio...
  • corv 12y ago
    Ok, I see.
  • brianwski 12y ago
    Brian from Backblaze here. Yep, we checksum the file on the client before sending it. In practice for any one user the number of "silent bit flips" on disk is very low and you probably wouldn't notice it (maybe 1 note in your mp3 file is slightly off). But when we check the checksums every few weeks we absolutely see it occur in our datacenter at our scale probably every day and take steps to heal the files (either from other copies we have or ask the client running on the customer's laptop to retransmit the file).