Pinboard (jm)
https://pinboard.in/u:jm/public/
recent bookmarks from jmMySQL Raft at Meta2023-05-17T09:04:10+00:00
https://engineering.fb.com/2023/05/16/data-infrastructure/mysql-raft-meta/
jmmysql ops replicas replication raft distributed-systems metahttps://pinboard.in/https://pinboard.in/u:jm/b:bc755bcb61b1/glibc changed their UTF-8 character collation ordering across versions, breaking postgres2019-01-11T11:19:17+00:00
https://www.postgresql.org/message-id/flat/BA6132ED-1F6B-4A0B-AC22-81278F5AB81E%40tripadvisor.com
jmStreaming replicas—and by extension, base backups—can become dangerously broken when the source and target machines run slightly different versions of glibc. Particularly, differences in strcoll and strcoll_l leave "corrupt" indexes on the slave. These indexes are sorted out of order with respect to the strcoll running on the slave. Because postgres is unaware of the discrepancy is uses these "corrupt" indexes to perform merge joins; merges rely heavily on the assumption that the indexes are sorted and this causes all the results of the join past the first poison pill entry to not be returned. Additionally, if the slave becomes master, the "corrupt" indexes will in cases be unable to enforce uniqueness, but quietly allow duplicate values.
Moral of the story -- keep your libc versions in sync across storage replication sets!]]>postgresql scary ops glibc collation utf-8 characters indexing sorting replicas postgreshttps://pinboard.in/https://pinboard.in/u:jm/b:7a5ed209308e/Hi-tech caves bring prehistoric Sistine chapel back to life2016-12-03T22:48:25+00:00
https://flipboard.com/@flipboard/flip.it%2FIg8lbY-hi-tech-caves-bring-prehistoric-sistine/f-79bc87cdd0%2Ftheguardian.com
jmSt-Cyr added: “It’s impossible for anyone to see the original now, but this is the next best thing. What is lost in not having the real thing is balanced by the fact people can see so much more of the detail of the wonderful paintings and engravings.”
]]>lascaux cave-art history prehistory caves replicashttps://pinboard.in/https://pinboard.in/u:jm/b:6d2fb48e6444/'Copysets: Reducing the Frequency of Data Loss in Cloud Storage' [paper]2013-07-08T13:34:40+00:00
http://www.stanford.edu/~cidon/materials/Usenix%20Final.pdf
jm
We present Copyset Replication, a novel general purpose replication technique that significantly reduces the frequency of data loss events. We implemented and evaluated Copyset Replication on two open source data center storage systems, HDFS and RAMCloud, and show it incurs a low overhead on all operations. Such systems require that each node’s data be scattered across several nodes for parallel data recovery and access. Copyset Replication presents a near optimal tradeoff between the number of nodes on which the data is scattered and the probability of data loss. For example, in a 5000-node RAMCloud cluster under a power outage, Copyset Replication reduces the probability of data loss from 99.99% to 0.15%. For Facebook’s HDFS cluster, it reduces the probability from 22.8% to 0.78%.
]]>storage cloud-storage replication data reliability fault-tolerance copysets replicas data-losshttps://pinboard.in/https://pinboard.in/u:jm/b:49c83e45080b/[tahoe-dev] erasure coding makes files more fragile, not less2012-03-27T23:19:15+00:00
https://tahoe-lafs.org/pipermail/tahoe-dev/2012-March/007185.html
jmerasure-coding replicas fs tahoe-lafs zooko monitoring devops opshttps://pinboard.in/https://pinboard.in/u:jm/b:554ffed32b31/