Yes, lots of people are using EC. Which is more “reliable” depends on what you need. If you need to survive 4 failures, there are scenarios where RF=3 won’t do it for you. You could in such a case use an EC 4,4 profile, 8,4, etc. It’s a tradeoff between write speed and raw::usable ratio efficiency. Which do you need more? Depending on your data, EC may increase space amp significantly. With RF=2 I have seen overlapping failures in my career. The larger the deployment, the greater the chance of overlapping failures. In a distributed system especially, RF=2 or EC with m=1 are bad ideas if your data is valuable.
On Nov 23, 2023, at 8:58 AM, Albert Shih <Albert.Shih@obspm.fr> wrote:
Hi everyone,
I just like to know what's your opinion about the reliability of erasure coding.
Of course I can understand if we want the «best of the best of the best» ;-) I can choose the replica method.
I heard in many location “replica” are more reliable, “replica” are more efficient etc...
Yes...well since 25 years I'm using raid (5, 6, lvm, raidz1, raidz2, etc.) I never loose data only once when a firmware bug in some xxxxx card crash the raid volume.
Now 25 years later lot of people recommend to use replica so if I buy XTo I'm only going to have X/3 To (vs raidz2 where I loose 2 disks over 9-12 disks).
So my question are : Anyone use in large scale erasure coding for critical (same level as raidz1/raid5 ou raidz2/raid6) ?
Regards -- Albert SHIH 🦫 🐸 Observatoire de Paris France Heure locale/Local time: jeu. 23 nov. 2023 14:51:28 CET _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-leave@ceph.io