Sunday, March 20, 2011

What should we contain Online Redo Log Files in Flash Disk?

I asked about How to use Flash Disk (Exadata)? on oracle-l - I think this may have benefit for someone. However, We should know about Flash Disk benefits on Oracle Database. and I have some question: What should we contain Online Redo Log Files in Flash Disk?

Online redo log files record all changes made to Oracle Database data files and control file. When a change is made to the database, Oracle Database generates a redo record in the redo buffer. Log Writer (LGWR) writes the contents of the redo buffer to the online redo log. LGWR performs sequential writes of redo to disk.

That's a concept what we know, and LGWR can perform fast sequential writes of redo to disk, the database improves performance.

A solid-state drive (SSD)
is a data storage device that uses solid-state memory to store persistent data with the intention of providing access in the same manner of a traditional block i/o hard disk drive. SSD has write speeds lower than its read speeds and sequential writes isn't better faster than Hard Disk.

So, I think It's not good idea to contain Online Redo Log Files in Flash Disk. How do you think?



Gary Myers said...

Guy Harrison had some info on this.

He came to the same conclusion, that the write penalty meant there probably wouldn't be a benefit.

Surachart said...

thank you so much

hmartinezlopez said...

they serve only to read, represent a difference of 200 to 10000 (aprox) with FC disks, making them ideal for flash "keep" cache...