ZFS or ASM - for Databases

-  ASM is Oracle special FS for only Oracle DB 
-  ZFS is general FS for any data , designed by Sun


-  When running Mysql, you cant use ASM, ZFS may be the choice.

-  When running Oracle RAC, ASM is only chance.

-  When running stand-alone Oracle, use ASM if better performance needed. 
 If performance is not so high, ZFS may also be a choice.



When using ZFS, for better performance, below advises are given. 
( Some are already implemented at ASM, read below. )

 - Create separate ZFS pools for each role ( TEMP,DATA,REDO,RECO,UNDO, INDEX etc.)
 - Use many separate LUNS in pools and use STRIPING. (asm already makes it)
	Pools with just one disk does not perform well and also gets limited to max 256 parallel SCSI commands per LUN
	Many LUNS ( at least 2 ) increases max parallel SCSI commands per LUN limit.
 - When you add a new LUN in a pool, better performance occurs if you rebalance data spreadness to all LUNS equally.
   (asm already has REBALANCING feature.)
 - use separate SSD disk for CACHE, to increase read performance
	zpool add myzpool cache /dev/ssd_drive_1
 - use separate SSD disks in MIRROR to be used in LOGGING, to increase write performance
	zpool add myzpool log mirror /dev/ssd_drive_2 /dev/ssd_drive_3
 - zfs recordsize (managed by OS admin) and DB blocksize ( managed by DB Admin) must fit.
   At ASM, there is no such parameter conflict problem degrading performance.
   (everything under control of DB admin)


We advise you to use always ASM with Oracle DB. 
This advise is made regarding performance and it does not consider licensing parameters.



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