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[其他] The Accidental DBA

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夏末聆听 发表于 2016-10-2 16:09:26
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This morning there was yet another comment thread on hacker news about Yet Another outage involving MongoDB and data loss, this time by some company called “CleverTap”.
  Recap

  To summarize: the CleverTap engineering team noticed that the WiredTiger storage engine was faster than MMAPv1 for MongoDB.  They decided to … “upgrade the following weekend” (that sentence alone made my eyes bulge).
   According to the blog post , they upgraded from 2.6 to 3.0, while simultaneously changing storage engines from MMAPv1 to WiredTiger, while leaving zero secondaries snapshot nodes with data on MMAPv1.  All over the course of 3 days.
   (They are also running sharded mongo, with a mere 300 ops/sec on each primary, which RAISES A LOT OF QUESTIONS but I already feel like I’m beating up on these kids so I won’t pursue that.)
  Questions …

     (But seriously what the *hell* can you be doing to have such a low request rate, that you
   
The Accidental DBA-1 (involving,summarize,following,weekend,running)
    need to shard at an infinitesimal volume?  Why did you specify it in req/min instead of req/sec?  What is the breakdown of reads/writes?  What is the lock percentage?  What is the avg object size??  Are these like multi-MB documents????  Why did you pause all incoming traffic and process it after the upgrade?  If the primary can’t take the extra load, why not rs.syncFrom() a secondary?   If that doesn’t work, don’t you have other, bigger problems??)
     Most bafflingly of all: why wait only a few minutes after electing a new WiredTiger primary for the  first time ever , and then immediately  DELETE your only known-good copies of the data on MMAPv1 and re-sync over them with WiredTiger?
  Accidental DBAs

  Okay.  So here’s the thing: you are clearly a team of accidental DBAs.  You are operations and software engineers who have found yourselves in charge of the data.
   It’s cool.  I am too!  It’s a really neat and fun place to be in.  DBAs and network admins are kind of the last remaining priesthoods in our industry.

The Accidental DBA-2 (involving,summarize,following,weekend,running)

   There’s a lot of powerful and fun stuff to be done for generalists who pick up specialty knowledge in one of those areas, or specialists (like my neteng friend Leslie ) who start bringing their skills back to the generalist side and merging the two.
  (Oh Right, We Wrote A Book About This!!!)

   My friend Laine and I are writing a book for people on the data side, called “ Database Reliability Engineering “, which is pitched towards generalists who want to learn how to deal with data responsibly and effectively.
   (Actually that’s a good point, I am supposed to be pitching this book, which is really
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。随便就好 发表于 2016-10-2 19:36:47
你拥有再大再多的水桶,也不如有一个水龙头。说明:”渠道很重要!
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xuchenmin123 发表于 2016-11-7 14:12:52
沙发抢不到,板凳也行啊!
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冒险家蜜蜜 发表于 2016-11-13 13:34:38
站位支持
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廖文熙 发表于 2016-11-14 16:08:36
很不错,谢谢夏末聆听的分享
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小清新 发表于 2016-11-15 09:05:49
顶顶更健康!
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wpctm 发表于 2016-11-18 17:15:48
幸好爱情不是一切,幸好一切都不是爱情。
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