Posts tagged flash cache

Oracle Database 11g Release 2: Flash Cache and Exadata V2

Sep 16th

Posted by Marco Gralike in General

1 comment

So, if I would wonder what is the purpose of this almost "hidden" feature called flash cache and were this came from (also see my post Oracle RDBMS 11gR2 – Flash Cache), now I know. I didn’t have the chance to follow Mr. Ellison’s launch event, but reading Alex Gorbatchev’s blog post on the Pythian web site Unveiling the OLTP Oracle Database Machine & Exadata v2 is enough explanation in the "why" and "how". Flash cache is one of the pillars that make the synergy with the Sun Exadata machine.

As Alex stated:

Exadata Storage Servers

Storage Servers are based on Sun Fire X4275. Again top of the shelf Intel Xeon 5500 Nehalem processors.

Capacity increased — SAS disks are 600 GB (+33%) and SATA disks are 2 TB which doubles what ODBM v1 offered. We all know that big disks are bad but that’s where Sun FlashWire technology comes into play with flash cache on the controllers (5+TB for the full ODBM).

This is what Ellison said about Flash cache:

“These are not Flash disks. Make no mistake — these are no Flash disks. This is a memory hierarchy made up of DRAM in our database servers and Flash in our storage servers with very sophisticated algorithms, not simple LRU — we know for doing a sequential scan, we don’t blow out the cache.”

I will be interested in what Larry has to say on his "traditional" Oracle Open World Thursday speech this year.  Exadata on Sun will probably be "old news" on that date/day. No need for hidden secrets to be announced via big "X" banners. The topic should be good for a 15 minutes or so to fill his speech and I still keep thinking, that on that day, Larry at least will pull one big "fresh rabbit" out of his magical hat.

In the meantime: "Wow, 5TB of flash cache to play with…"

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Oracle RDBMS 11gR2 – Flash Cache

Sep 1st

Posted by Marco Gralike in General

5 comments

I noticed yesterday a new feature that could have the potential to be a small, by me unnoticed, gem called "Flash Cache". I hope someone on the internet, that has tested it, will post his or hers experiences on this…

While using DBMS_METADATA:

select dbms_metadata.get_ddl('TABLE','MYDATA', user) from dual;

DBMS_METADATA.GET_DDL(‘TABLE’,'MYDATA’,USER)
——————————————————————————–

  CREATE TABLE "XMLDB_USER"."MYDATA"
   (    "ID" NUMBER(9,0),
        "DOC" "SYS"."XMLTYPE"
   ) SEGMENT CREATION IMMEDIATE
  PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255 NOCOMPRESS NOLOGGING
  STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
  PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT
   FLASH_CACHE DEFAULT
   CELL_FLASH_CACHE DEFAULT)
  TABLESPACE "XML_DATA"
  XMLTYPE COLUMN "DOC" STORE AS SECUREFILE BINARY XML  (
  TABLESPACE "XML_DATA" ENABLE STORAGE IN ROW CHUNK 8192
  NOCACHE NOLOGGING  NOCOMPRESS  KEEP_DUPLICATES
  STORAGE(INITIAL 106496 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
  PCTINCREASE 0 BUFFER_POOL DEFAULT
   FLASH_CACHE DEFAULT
   CELL_FLASH_CACHE DEFAULT
  ))
  XMLSCHEMA "http://www.myserver.com/MySchema.xsd" ELEMENT "ROOT"
  DISALLOW NONSCHEMA

So I looked it up in the 11gR2 manuals:

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