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theoretic question [message #564548] Sat, 25 August 2012 07:31 Go to next message
piotrtal
Messages: 152
Registered: June 2011
Location: Poland/Czestochowa
Senior Member

some months ago i planned to deploy two RAC installations only for test purposes - just to play with them. i assumed that both of them will be different with theirs architecture.

first one:
--------------
OEL5.5
11.2.0.3
2 nodes
externall storage based on ISCSI + ASM and ASMlib
separate oracle homes on both nodes

second one:
--------------
OEL4.5
10.2.0.1
2 nodes
nfs from third server as external storage
common oracle home stored on shared storage

and to tell you the true i supposed that the second installation will be much more difficult to deploy that first one. but i was wrong.
NFS as shared storage is much more easy to deploy and maintanance - and this is my assumptions after physical deployment of this two RAC's.

lets not talk about redudundancy and performance between this two installations, but lets take under consideration its easy deployment and easy maintanance.

in my opinion using NFS as shared storage is much more easy and not as effort demainding than deploying RAC on ASM. it doesn't require ASM installation, files are stored on separate NFS share where we can see them from the operating system level and even installation is much more simpler.
what do you think about that?

how many RAC installation is deployed using ASM+ISCSI/FC comparing to NFS as external storage.
is it allowable considering RAC installation with NFS as external storage as something less profesional than storing datafiles on ASM in DiskGroups?

what do you think about cons and pros comparing this thwo architectures?

[Updated on: Sat, 25 August 2012 08:00]

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Re: theoretic question [message #564553 is a reply to message #564548] Sat, 25 August 2012 10:39 Go to previous messageGo to next message
John Watson
Messages: 4693
Registered: January 2010
Location: Global Village
Senior Member
A few thoughts that might help you decide:
Quote:
NFS as shared storage is much more easy to deploy and maintanance
It might be easier for you, because you don't have to do the work. You are passing the work back to your system administrators.
Quote:
lets not talk about redudundancy and performance between this two installations,
Why not? These are two of the most important reasons for using RAC.
Quote:
in my opinion using NFS as shared storage is much more easy and not as effort demainding than deploying RAC on ASM.
your client will not be impressed when you explain that your reason for recommending something is that it will make your job easy.
Quote:
how many RAC installation is deployed using ASM
in my experience, nine out of ten.
Quote:
what do you think about cons and pros comparing this thwo architectures?
Look at what you can do when you place your storage under Grid Infrastructure control, and the answer will be obvious.
Re: theoretic question [message #564583 is a reply to message #564553] Sun, 26 August 2012 03:42 Go to previous messageGo to next message
piotrtal
Messages: 152
Registered: June 2011
Location: Poland/Czestochowa
Senior Member

Quote:
Quote:
lets not talk about redudundancy and performance between this two installations,
Why not? These are two of the most important reasons for using RAC.


this disscusion is only for understand some facts about NFS/OCFS vs ASM by me, so don't take it personally - this is not attack on anyone as a person. Smile
i just need to understand some facts which messed in my mind after i installed some RAC's to play with them. so everyone, please straighteen my imporper reasoning and don't be angry on me.

we can always have external redundancy on physical storage device which should be easier to maintain and performance better. i could agree with sentence "ASM redudancy is better than external" only in one case: if company doesn't posess storage administrator but only DBA <-- in that case i would agree Smile

about NFS vs ASM performance won't discuss, because i don't possess data about it's difference with performance. i could only presume that ASM is better but question is: "it is so much performance better that it is worth to install ASM instance on each node to maintain disgroups, and diminish capacity of each node at the same time?" each of ASM instance utilizes ressources (memory/cpu) on node and it could be considered as disadvantage.

you told about many features which ASM gives over NFS/OCFS, and i would agree only with one - maybe performance. redundancy and stripping we can do on physical level.
if i have datafiles stored on OS level instead ASM i would consider this as advantage, because (its my opinion) it easier to maintain files when we have them on OS level.

even if we consider extensive remote RAC installation (one node is far /distance/ from the other) and we have read-preffered storage parameter set for each ASM instance i wouldn't agree. the same we can obtain on harware level. EMC storages could also replicate between sites, and i don't believe that this hardware replication is worse than software ASM replication.

so i would say that i don't see pros for ASM at this moment (probably because i don't have experience with RAC's). maybe performance is better, but presumably not too much (i didn't find comparisons on internet). but performance is not only one think which we should take under consideration during deployment. there is much more factors to consider - if company possess unix/linux and storage specialist, it is completely unreasonable to do duplication on ASM level and store datafiles in diskgroups.

Quote:

Quote:
what do you think about cons and pros comparing this thwo architectures?
Look at what you can do when you place your storage under Grid Infrastructure control, and the answer will be obvious.


i don't see this what i can do using ASM instead NFS/OCFS.
maybe do you mean Oracle Enterprise Manager Grid Control?

[Updated on: Sun, 26 August 2012 04:00]

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Re: theoretic question [message #564584 is a reply to message #564583] Sun, 26 August 2012 04:26 Go to previous messageGo to next message
John Watson
Messages: 4693
Registered: January 2010
Location: Global Village
Senior Member
Er... your closing sentence suggests that you do not know what Grid Infrastructure is. That might explain why you have to ask this question. Better do some studying!
Re: theoretic question [message #564585 is a reply to message #564584] Sun, 26 August 2012 04:46 Go to previous message
piotrtal
Messages: 152
Registered: June 2011
Location: Poland/Czestochowa
Senior Member

John Watson wrote on Sun, 26 August 2012 11:26
Er... your closing sentence suggests that you do not know what Grid Infrastructure is. That might explain why you have to ask this question. Better do some studying!



thanks John for answer.

which one sentence suggest that i need to studing?:

this --> i don't see this what i can do using ASM instead NFS/OCFS.

or this: --> maybe do you mean Oracle Enterprise Manager Grid Control?

if this first one - i don't agree. i just don's see advantages of ASM over NFS. in both cases i need to use GI so GI is out of discussion.

but if second one: it was question mark at the end. i didnt suggest that OEMGC equal GI. i just suggested that one of prons could be using OEMGC as a tool for displaying many intertesting information of our ASM instances in our RAC enviroment.
i am sure that i know well role of Grid INfrastructure in RAC environment. this topic wasn't created about GI but about ASM and sense of using it instead of NFS. as i said GI is out of discussion.

[Updated on: Sun, 26 August 2012 04:50]

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