Jonathan Lewis explains Delphix
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Delphix: the eternal rolling testbed Jonathan Lewis explains how Delphix data virtualization and instant cloning works
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Jonathan Lewis explains Delphix
- 1. Delphix The Eternal Rolling Testbed Jonathan Lewis jonathanlewis.wordpress.com www.jlcomp.demon.co.uk
- 2. Delphix Testbed 2 / 18 Who am I ? Independent Consultant 31+ years in IT 26+ using Oracle Strategy, Design, Review, Briefings, Educational, Trouble-shooting Oracle author of the year 2006 Select Editor’s choice 2007 UKOUG Inspiring Presenter 2011 ODTUG 2012 Best Presenter (d/b) UKOUG Inspiring Presenter 2012 UKOUG Lifetime Award (IPA) 2013 Member of the Oak Table Network Oracle ACE Director O1 visa for USA Jonathan Lewis © 2013 - 2014
- 3. Delphix: Nearly instant access to N+1 different versions Delphix Testbed 3 / 18 What do you gain ? Backups: One at Level 0 + N at Level 1 = ? Traditional: A long restore/recover to one specific version Jonathan Lewis © 2013 - 2014
- 4. Windows 7, VMWare Server 2.0 - 16GB RAM, 4 CPU, 2 x 500GB drives OEL 5.6 VM Oracle 11.2.0.4 Delphix Testbed 4 / 18 What do you need ? Production: s/w and database with "delphix" a/c Jonathan Lewis © 2013 - 2014 Delphix VM Backups and virtual databases OEL 5.6 VM Oracle 11.2.0.4 Development: s/w and config files with "delphix" a/c
- 5. If you know how Basicfile LOBs work, you know the basics of DxFS. Delphix Testbed 5 / 18 DxFS for DBAs Jonathan Lewis © 2013 - 2014 key = LOB id key = timestamp LOB Segment Current chunks Previous chunks LOB Index Segment High Water Mark
- 6. t0 Metadata (associates logical block with physical location) a b c d e f g h i Filesystem data blocks (Variable number of sectors per block) Delphix Testbed 6 / 18 DxFS Jonathan Lewis © 2013 - 2014 Set the DxFS block size to match the database block size. DxFS blocks are transparently compressed to the smallest number of sectors possible.
- 7. "Modifications" t0 t1 a b c d e f g h i Delphix Testbed 7 / 18 Jonathan Lewis © 2013 - 2014 b' c' Data only becomes visible when root block is written You don't overwrite blocks on disc with a new version, you write a new copy and maintain the index (and you don't overwrite index blocks either).
- 8. Multi-versioning t1 a d e f g h i Delphix Testbed 8 / 18 Jonathan Lewis © 2013 - 2014 b' c' This is the latest state of our file system - but we don't have to release the old versions of the blocks we "changed".
- 9. t1 t0 a d e f g h i Delphix Testbed 9 / 18 Aging data Blocks that can be freed when we don’t want the older snapshot any more Jonathan Lewis © 2013 - 2014 b c b' c' Over time we may "overwrite" many of the most recent blocks, and be able to free old copies of those blocks, keeping a lot of the oldest original blocks
- 10. Working with Oracle • Start with a complete rman backup • Take regular incremental backups – Delphix has custom code to apply them efficiently • For a vDB pick a recovery point – Delphix code configures the target server, sets an instance there, and exposes the right version of data – The data stays on the Delphix Server Delphix Testbed 10 / 18 Jonathan Lewis © 2013 - 2014 Time for a demonstration: (identify source and target machines, identify source d/b, create first backup, create vDB).
- 11. Delphix Testbed 11 / 18 Traditional Backups Level 0 Level 1 Jonathan Lewis © 2013 - 2014 Data Redo Level 1 Data Redo Level 1 Data Redo Redo To get a new database you restore the level 0 image and apply as many level 1 images as needed - and you've got one version of the database available.
- 12. Delphix Testbed 12 / 18 Delphix Backups Level 0 Level 1 Jonathan Lewis © 2013 - 2014 Data Redo Level 1 Data Redo Level 1 Data Redo Redo Delphix unpacks the rman backups as they are generated and applies them (excluding redo) to the level 0 backup.
- 13. Delphix Testbed 13 / 18 Delphix Backups Jonathan Lewis © 2013 - 2014 DxFS doesn't overwrite changed blocks, though, it writes them to a separate location and creates some new index entries.
- 14. Delphix Testbed 14 / 18 Delphix Backups Jonathan Lewis © 2013 - 2014
- 15. Delphix Testbed 15 / 18 Delphix Backups Jonathan Lewis © 2013 - 2014
- 16. Redo Rolling forward creates some new (f/s) blocks and pointers, and a new root block. Every new vDB gets its own "index root block". Delphix Testbed 16 / 18 Pick your version Pick an index to create your vDB Jonathan Lewis © 2013 - 2014 Redo Redo Redo Delphix rolls forward (and back) from the associated redo
- 17. Delphix Testbed 17 / 18 Rolling history Jonathan Lewis © 2013 - 2014 Redo To delete history Delphix can do an optimised walk of "old" indexes and delete any blocks for which a newer block has been created.
- 18. What have you got ? • Same backups, on a different device • DxFS compression may save space • Quick and easy to create a new test d/b • EVERY version can exist simultaneously Delphix Testbed 18 / 18 – multiple times for multiple independent users Jonathan Lewis © 2013 - 2014
Hinweis der Redaktion
- I used an ISO to install Delphix so I selected Sun Solaris 10 from the VMWare list of O/S options. At the time of speaking (Sept 2014) the latest version of Delphix is 4.2
- LOBs replace longs and have much greater flexibility and more efficient storage. In particular they can be updated piecewise, need not go through the buffer cache, and need not be logged - but this last option may result in lots of control file writes as Oracle updates the unrecoverable SCN for the target file on every update (Steve Adams). (Avoiding the cache also seems to have surprising and undesirable I/O overheads at present as well, and there is a cache reads option in recent versions of Oracle which may help a little). create table t1 (text_content clob) lob (text_content) store as text_lob( disable storage in row chunk 32K -- current maximum (default 1 block) pctversion 25 -- space allowed for old copies (default 10) nocache nologging -- possibly a bad idea (default cache logging) ); The largest chunk size is 32K - which seems small for a "large object". To track LOB chunks Oracle uses an index which is forced into the same tablespace as the LOB itself - which results in two conflicting uses of a tablespace. There is some confusion about space wastage and re-use, and a new type of snapshot too old error message (ORA-22924). Oracle 9.2 has a retention time option for LOBs, (pctversion is still available), and a freepools count rather than freelist groups to reduce space allocation problems under RAC. These features are only available under automatic undo; but you will still run into performance problems if you insert lots of LOBs in a highly concurrent system. Large blocks may ease the problem slightly. Suggested strategy: to handle lots of small files - store them as LOBs inside the database, Oracle is good at cataloguing (indexing) and the file system is not. For a small number of large objects store them as BFILEs outside the database, Oracle introduces an overhead for no benefit.
- It may be possible to store completely empty Oracle pages in the metadata entry of the block.
- See: https://blogs.oracle.com/ahrens/entry/is_it_magic