Posts tagged flash cache
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 More >
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;
CREATE TABLE "XMLDB_USER"."MYDATA"
( "ID" NUMBER(9,0),
) 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
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
XMLSCHEMA "http://www.myserver.com/MySchema.xsd" ELEMENT "ROOT"
DISALLOW More >