http://www.linkedin.com/groups/ACFS-OCFS-Which-one-is-3156190.S.107915056

That is ASM=Cluster File System + Volume Manager. 

Oracle binaries directly talks with Database files in ASM diskgroup using ASM instance.ASM itself automatically mount all partitions without third party intervention. 

For OCFS it uses OS to mount all partitions and use OS to locate them. 

ASM has functionality of Mirroring and Stripping concept to reduce IO intervention. 

These reasons ACFS is Faster than OCFS FileSystem. 

Raw FileSystem is also faster than OCFS FileSystem...===============================================================.

The original question really doesn't make sense. There are 3 different technologies that are being discussed here, and the differences are important. 

OCFS - general purpose CFS - can be used for database and non-database files - included in the Linux kernel - only available on Linux or Windows - uses its own 'clusterware' - can be useful if migrating from a traditional filesystem based environment with a lot of legacy scripts etc 

ASM - can only be used for database files, both RAC and non-RAC. Included in the Oracle Grid Infrastructure on all supported platforms - preferred technology for database storage 

ACFS - CFS built on top of ASM - you could look at it as ASM manages the physical devices, ACFS is LVM - cannot be used for database files - not available on all platforms 

and while we are discussing it, there is also now DirectNFS in the mix. 

I suspect they wanted to know the difference between ASM and OCFS for the database, and I suspect the true answer, like a lot of questions about Oracle, is 'It depends...' 

As to whether 'Raw FileSystem is also faster than OCFS FileSystem' I believe the differences are marginal, and are far outweighed by the difficulty in managing raw devices (not to mention they are not really supported anymore)

My best answer in this situation would be a set of questions: "Well ... that depends on a lot of things. What are you intending to use ACFS vs. OCFS2 for? Are you intending to store a database's datafiles, control files, or redo logs on the file system? What kind of speed and throughput do we need, and why?" 

Frankly, ACFS is specifically aimed at storing non-Oracle database files (e.g. configuration files and binaries for application files) because of its snapshotting features. I don't see a lot of value for ACFS in an Oracle database realm because ASM is aimed directly at efficient I/O for Oracle database files. The Exadata DBM doesn't even permit ACFS to be used, so I'm not sure that ACFS is a likely candidate for many useful purposes in the multi-TB or -PB range.

LiShan ChengTechnical Manager at ORAUX

I had to use OCFS2 for UTL_FILE for my last 11gR2 RAC implementation because the customer was told that if they wanted to use ACFS for UTL_FILE they had to pay for licenses. A pain. Also OCFS2 usually works ok but if the I/O load is high we might see evictions due to the disk heartbeat works 

A few years ago I was implementing Extended RAC 10gR2 and we used NAS for UTL_FILE, external tables and backup purposes.

Deepak Sankpal, PMP, ITILExperienced Database Analyst

Comparing ACFS to OCFS is like comparing Apples to Oranges. No doubt ACFS is the best. OCFS is old. ACFS is a layer on Oracle ASM. There are a number features and advantages ACFS offers such as: 

- General purpose filesystem for non-DB files. ACFS is a multi-platform, scalable file system that extends Oracle ASM functionality to support files maintained outside of the database. - Dynamic filesystem resizing. - High Performance. - Supports NFS and CIFS protocols. - Advanced features: Snapshot, Replication, Tagging, Security and Encryption. - Starting with 11.2.0.3, ACFS supports RMAN backups, archive logs, and Data Pump dumpsets.

OleksandrOleksandr Denysenkooracle: consulting, outsourcing and support services in Ukraine

ChandraSekhar,I think that it was an indirect question - You have to discuss benefits and drawback of each product,but not really provide direct answer to this question because it's even impossible to do benchmarks in some casesjust a short summary on already provided info my $0.02:

* OCFS doesn't directly relates to 11g release 2, but ACFS was introduced in 11.2

* ACFS doesn't support database files, but OCFS - does - how to do benchmarks ?

* OCFS runs only on Linux Windows

* OCFS has it's own cluster that may decide that it's time to reboot even everything seems ok

* OCFS has some claims on it's stability, especially during high workload

* ACFS now requires licensing as Cloud FileSystem, but OCFS is free

* ACFS has built in mirroring on ASM level, OCFS doesn'tand this mirroring may be used with disk systems distributed over 2 different sites - for disaster recovery

* ACFS has built in snapshot support, OCFS doesn't

* ACFS just can't be 10x faster than OCFS- as always - 'It depends...'

Horacio MirandaSenior Oracle DBA at Unisys

uff, look like we need to start from scratch here, as Oleksandr say before agree they ask OCFS vs ACFS to check your background and how old you are with Oracle. OCFS from the time or RAC 9i, 10G use ASM and 11G use OCFS. Also if the interview is related to EBS R12 or 11i ACFS it is not supported at all. Oracle support OCFS only. ( why, ACFS perform badly when strike 100% specially if you share this ACFS over NFS ( what work at kernel level ), the real explanation here is more complicated ( we can open a thread about what/why ACFS vs OCFS and what happens if.... 

They key factor here is the way you answer the interview and how much you know about products ( how to use them ) as Oracle sale boxes and you use the boxes as the recommendations from the vendor, for this case Oracle. 

If some ask what is better, you need to say what ever it is certified

and supported for your solution, bits more bits less (ACFS or OCFS ) doesn't really care if the vendor support the components. 

Just keep on mind. the concept is CFS ( cluster File system ) use OCFS, ACFS, VeritasFS, AdvanceFS ( tru64 ) doesn't really matters as they share the filesystem across the nodes. ( GFS, or CXFS from silicon Graphics they works ) but Oracle at the moment support ACFS and OCFS for some products, read about what is certified and stick to short answers as long answers are not good in the interviews). Remember the two goals for the DBAS are ( keep the database up and running well, performance and good response time ), and the second goal is have a escape plan ( backups, ) think two times if your backups are ready to rebuild your system if someone stole the server or the datacenter strike a earthquake. ( send backups to a secure place )... hardware or technology is not important at the time of the problems. Data is what Oracle protect and Oracle have several ways to protect data. What technology you use to run, doesn't really matters just stick to what is certified ( sorry for say this again ). I hope this answer make more clear what you need to answer to make more clear you know about this subject.

HoracioHoracio MirandaSenior Oracle DBA at Unisys:( Sad face for this comment. The main reason why ACFS is not certified for EBS even if U share ACFS across the apps nodes using NFS, ( the only way so far ), is because the NFS is a kernel module. Means. 1.- Kernel 2.- NFS module 3.- ASM 4.- ACFS 

If the NFS module lost the filesystem ( something happens to

the ACFS ) the kernel will be busy waiting for IO, as the ACFS works over the ASM layer you will strike a dead lock there. ( until the point to make the node reboot ). 

Do the lab and see whats happens. 

And U can't recommend unsupported or UN-certified solutions for your customers as at the end Oracle will say it is not supported. Be careful with what U recommend. Please remember if something works doesn't mean will work well. Stress the system EBS with ACFS over NFS and check whats happens. Of course U can't put the apps and the DB in the same cluster ( as that is not what Oracle recommends with DBTier and APPSTier).

HoracioHoracio MirandaSenior Oracle DBA at Unisys

please check how NFS-ACFS perform under the following scenarios. 1.- Make the Filesystem ACFS strike 100%, check how nfs performs. 2.- use shared APP TOP and check how the response time of some call in the apps server perform over the ACFS. (performance issue in the ACFS when you have over 200K files per directory). 3.- Fail over test, if you allocate a NFS service (using the cluster service of grid). and create a VIP in order to resist the lost of the NFS Server (example node1) the response time when the service move from node 1 to node 2, will be around 2 min. the problem as soon you get the service back the nfs_lock have the pointer still open, so you are no able to write the same file (is lock). 4.- Under read/write stress situation, the ACFS will not respond faster, as NFS works as a Kernel module, the NFS have priority over the DISK IO of the ACFS (as ACFS is a

program using the ACFS lib ). so both resources will fight for IO at kernel level, the kernel doesn't know the ACFS have priority here. As the cluster is not able to write into the ASM voting disk only after 29 seconds of really stress the node will reboot. Similar situation over OCFS (old OCFS version 1.4 I think, the one used with RAC 9i). Check this four points. ACFS if a good solution but how the EBS works, I don't think is the best mix ACFS-NFS.Senior Oracle DBA at Unisys

The worst case scenario is totally lost of the storage. And for that scenario you need a backup of the FS. 

CFS (Cluster FileSystem ) doesn't mean the data will be protected 100% just two o more servers can access the same filesystem. VCFS, CXFS, GFS, OCFS, ACFS, etc. If you lost the data layer then you can get the backups. 

But to answer your question, if you lost the OS layer only, but the ASMdisks are 100% OK, then you need to follow a disaster recover scenario. ( but trust me, nothing is better than a backup ).

Horacio MirandaSenior Oracle DBA at UnisysI think I was lost when I read some opinions related to OCFS vs ASM, the main thing here is the answer to the original question. "ACFS and OCFS : Which one is the fastest in running and best in performance in 11g release 2 ?It was asked in interview". 

And the best answer I thinks, come from you Will. 

Perhaps a good answer may include all/some the followings points. 

May be a complete answer will include. 0.- Explain you can have double or triple mirror of the data, feature only for ASM. 1.- opinion (geek version but 1 or 2 min ). 2.- Check if the products using the database are certified with ASM or OCFS" 

3.- problems : Is well know under heavy load the OCFS will reboot notes. ( over 9i ) 4.- Follow the recommendation of the vendors, and keep the contact numbers if the vendor recommends something that is not working properly. 

I think a best answer will include all this points.

Sr. Oracle Applications DBA at Carnival Cruise Lines

@Horacio - #2 is a good point. (all of them are, actually) 

Companies need to deliver solutions, but they are primarily interested in managing risk. Running an uncertified configuration is pretty high on the risk meter. 

For instance, Oracle ACFS was not certified for the appsTier on EBS when we considered it in late 2012. I don't know the current status. I used to try to stay up on everything, but there's too much. These days, I check the certification whenever we have to make a decision. 

Back to the interview, you don't have to know everything about OCFS and ACFS certification. If you think you know, you can say, "I don't think ACFS is certified…" or you can say, "isn't there a problem with OCFS rebooting under load?". My point is you don't have to be an expert. Just hit on everything that you'd consider when you make this type of decision.