#1 option looks more predictable. But it's possible to add a message "for better IO performance please migrate to 4K-pages".
BR, Serge On Wed, 16 Aug 2017 at 03:46, Dmitriy Setrakyan <dsetrak...@apache.org> wrote: > I like #1 if possible. Of course, if the LFS is empty, then the new default > should be 4k. > > On Tue, Aug 15, 2017 at 12:01 PM, Ivan Rakov <ivan.glu...@gmail.com> > wrote: > > > Guys, > > > > We have benchmarked how checkpoint write speed on SSD disk depends on > > various parameters. It became absolutely obvious that using 4K pages in > > durable memory instead of 2K brings considerable, significant speed-up. I > > think, we must set 4K as default page size. > > Ticket with detailed explanation: https://issues.apache.org/jira > > /browse/IGNITE-5884 > > Spoiler: it depends on write order and alignment, but writing 4K is at > > least *3x faster* than writing 2K when other parameters are the same. > > > > The question is backwards compatibility. If pageSize is not explicitly > set > > in user configuration, attempt to start "4k default" Ignite node from "2k > > default" LFS files will fail with exception: > > > > class org.apache.ignite.IgniteCheckedException: Failed to verify store > >> file (invalid page size) [expectedPageSize=4096, filePageSize=2048] > >> at org.apache.ignite.internal.processors.cache.persistence.file > >> .FilePageStore.checkFile(FilePageStore.java:206) > >> at org.apache.ignite.internal.processors.cache.persistence.file > >> .FilePageStore.init(FilePageStore.java:416) > >> at org.apache.ignite.internal.processors.cache.persistence.file > >> .FilePageStore.read(FilePageStore.java:315) > >> at org.apache.ignite.internal.processors.cache.persistence.file > >> .FilePageStoreManager.read(FilePageStoreManager.java:287) > >> at org.apache.ignite.internal.processors.cache.persistence.file > >> .FilePageStoreManager.read(FilePageStoreManager.java:272) > >> at org.apache.ignite.internal.processors.cache.persistence.page > >> mem.PageMemoryImpl.acquirePage(PageMemoryImpl.java:569) > >> at org.apache.ignite.internal.processors.cache.persistence.page > >> mem.PageMemoryImpl.acquirePage(PageMemoryImpl.java:487) > >> at org.apache.ignite.internal.processors.cache.persistence.Grid > >> CacheOffheapManager.getOrAllocateCacheMetas(GridCacheOffheap > >> Manager.java:515) > >> at org.apache.ignite.internal.processors.cache.persistence.Grid > >> CacheOffheapManager.initDataStructures(GridCacheOffheapManager.java:86) > >> at org.apache.ignite.internal.processors.cache.IgniteCacheOffhe > >> apManagerImpl.start(IgniteCacheOffheapManagerImpl.java:139) > >> at org.apache.ignite.internal.processors.cache.CacheGroupContex > >> t.start(CacheGroupContext.java:868) > >> > > > > I think, we have two options here: > > > > 1) Obvious and safe - provide silent backwards compatibility. We can > > implement a task which will find any LFS file, check its pageSize and use > > it as default. > > 2) Less user-friendly, but in my opinion still better option - crash > node, > > but make error message more informative. We'll let user know that default > > pageSize was changed to 4k due to discovered performance boost on most > > UNIX-based enviroments with SSD (which is for sure most popular > enviroment > > among users), and recommend user to migrate to 4K-page LFS. If user still > > wants to work with 2k pages, he can always set it explicitly in > > MemoryConfiguration and start node. > > > > Thoughts? > > > > -- > > Best Regards, > > Ivan Rakov > > > > >
