Обсуждение: New wiki page on write reliability
Now that some of my recent writing has gone from NDA protected to public sample, I've added a new page to the PostgreSQL wiki that provides a good starting set of resources to learn about an ever popular topic here, how write cache problems can lead to database corruption: http://wiki.postgresql.org/wiki/Reliable_Writes Bruce also has a presentation he's been working on that adds pictures showing the flow of data through the various cache levels, to help people visualize the whole thing, that should get added into there once he's finished tweaking it. I'd like to get some feedback from the members of this list about what's still missing after this expanded data dump. Ultimately I'd like to get this page to be an authoritative enough resource that the "Reliability" section of the official documentation could point back to this as a recommendation for additional information. So much of this material requires singling out specific vendors and staying up to date with hardware changes, both things that the official docs are not a good place for. -- Greg Smith, 2ndQuadrant US greg@2ndQuadrant.com Baltimore, MD PostgreSQL Training, Services and Support www.2ndQuadrant.us Author, "PostgreSQL 9.0 High Performance": http://www.2ndquadrant.com/books
On 10-10-21 10:08 AM, Greg Smith wrote: > Now that some of my recent writing has gone from NDA protected to > public sample, I've added a new page to the PostgreSQL wiki that > provides a good starting set of resources to learn about an ever > popular topic here, how write cache problems can lead to database > corruption: http://wiki.postgresql.org/wiki/Reliable_Writes > > Bruce also has a presentation he's been working on that adds pictures > showing the flow of data through the various cache levels, to help > people visualize the whole thing, that should get added into there > once he's finished tweaking it. > > I'd like to get some feedback from the members of this list about > what's still missing after this expanded data dump. Ultimately I'd > like to get this page to be an authoritative enough resource that the > "Reliability" section of the official documentation could point back > to this as a recommendation for additional information. So much of > this material requires singling out specific vendors and staying up to > date with hardware changes, both things that the official docs are not > a good place for. > Looks like a good start. I think a warning turning fsync off, the dangers of async_commit, and the potential problems with disabling full_page_writes might be worth mentioning on this page, unless you want to leave that buried in the attached references. -- Brad Nicholson 416-673-4106 Database Administrator, Afilias Canada Corp.
Brad Nicholson wrote: > I think a warning turning fsync off, the dangers of async_commit, and > the potential problems with disabling full_page_writes might be worth > mentioning on this page, unless you want to leave that buried in the > attached references. Good idea to highlight that. What I just did here was point out which of the references covered that specific topic, which is as good as I could do for now. It's hard for me to justify spending time writing more about those when they are covered in the attached references, and I personally can't do it because of my publishing agreement. The fact that the information about this topic is what ended up being released as the sample material from my book is not coincidence--I wanted to be able to share what I'd done here as a free community resources because this topic is so important to me. But I can't go much further than what I've already put up there myself. -- Greg Smith, 2ndQuadrant US greg@2ndQuadrant.com Baltimore, MD PostgreSQL Training, Services and Support www.2ndQuadrant.us
Greg Smith wrote: > Now that some of my recent writing has gone from NDA protected to public > sample, I've added a new page to the PostgreSQL wiki that provides a > good starting set of resources to learn about an ever popular topic > here, how write cache problems can lead to database corruption: > http://wiki.postgresql.org/wiki/Reliable_Writes > > Bruce also has a presentation he's been working on that adds pictures > showing the flow of data through the various cache levels, to help > people visualize the whole thing, that should get added into there once > he's finished tweaking it. My presentation is done and is now on the wiki too: http://momjian.us/main/writings/pgsql/hw_selection.pdf -- Bruce Momjian <bruce@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + It's impossible for everything to be true. +