Smart Flash Cache and redo with SSD
oraLaroOct 23 2012 — edited Oct 23 201211.2.0.2.0
OEL.
Design stage of New SAN. I can put a lot of the database, including redo on SSD. 2 questions.
1. Hardware sub tiering enabled. Has anyone ever gauged performance with enabling 11g Smart flash cache using the SSD as the flash device even with the hardware subtiering on? ie, if the hardware subtiering is moving hotblocks to most performant disk, is there much significant benefit having the flash cache on. Im guessing yes as the flash cache is working at the SGA level. Appreciate if anyone has any formulated thoughts on it.
2. To redo or not to redo on SSD. Many notes say not to so as to avoid log file sync waits. Is there a way to keep it on the SSD and avoid the waits? Is there any risk of enhanced degradation of the disks over time with having so much sequential writes from the redo if I leave it on there?
How to Minimise Waits for 'Log File Sync' [ID 857576.1] (discusses keeping redo off ssd but only generally)
this is a decent example of why to put on SSD.
http://communities.intel.com/community/datastack/blog/2011/11/07/improve-database-performance-redo-and-transaction-logs-on-solid-state-disks-ssds