Row Device vs File System

[saju_2]

Hi mehul

I think u already got the answer for difference between RAW and FS.
I found an article in net which was discussing about either to use DB as RAW or FS. Pls check this attachment.

Regards
CS

[saju_2]

Hi all

The same attachment which i posted is already attached by Jean-Luc.. Sorry guys..

Regards
CS

[Yogeeraj_1]

hi mehul,

they have been Raw Device and File system, now there is ASM (Automatic Storage Management). A thing that you must not ignore now with Oracle Databases!

In fact Oracle allows you to use all of them. TPC results have show that ASM is on the "large end".

ASM also brings along the following advantages:
o Management Capabilities
The administration layer has been removed so that DBA gets the hand, the System administrator is least involved. The DBA manages storage for the thing that uses more storage than anything else in your system (the database). There are less moving pieces.

o Availability
It provides for database level mirroring of database data. It is mirrored and then striped (instead of striped and mirrored) meaning if you lose a 9GB drive in the array, you don't need a hot spare sitting around -- we just need 9 gig of storage somewhere in the system on other failure groups in the disk group. You need to get a new 9gig drive soon, but you don't lose protection just because you lost a disk and didn't have an entire blank one sitting around.

You can also for instance ONLINE migrate your NAS to a SAN. You just have to add the SAN storage to the disk group, drop the NAS storage and the database will move all data from "hardware A" to "hardware B".

o Performance.
There is no man in the middle with ASM. It does not have the overheads associated with file systems (the latter just manages sections of disk that are made of pages in things called files).

hope this helps too!

kind regards
yogeeraj

[Arunvijai_4]

What Tom says ?

http://asktom.oracle.com/pls/ask/f?p=4950:8:::::F4950_P8_DISPLAYID:7931107631402

-Arun

[Frank de Vries]

I worked with both but I see that raw devices are more and more phased out.

I think this makes sense since technology
to disks has improved a lot I find that raw devices became something of the passed when I/O buffer memory was significant performance factor. And so as a DBA you didn't mind to sarcrifice conveniance for
performance.

Nowadays with high scsi or even fiber throughput to a san disk cluster (Hp, EmC or
Toshiba) and also the later versions of Oracle became more sophisticated in regards to disk i/o so that raw devices are no longer a sexy performance solution.

So it does no longer make sense to surrender
transparency and easier database managemant
for the (once) performance gain by using
raw devices.

One more comment: The best performance gain
is still achieved in writing better i/o
efficient code.

Hope this gives you a better philosophical
basis to your decision making process and choices at hand.