Karim, This is one big environment.
I dont see how ASM over OCFS2 would give easier administration than only ASM or only OCFS2. The only situation I see that is reasonable to use ASM over a cooked filesystem would be when using a NAS device that doesnt support direct block access. Also I dont understand why you say that RAC needs a shared filesystem. When you use ASM you dont need to have a shared filesystem. If you go ASM, you will need to install the cluster services on each server that shares a ASM diskgroup, even if it has no RAC databases. The same goes to OCFS2, you will need to install the OCFS2 services on each server that shares a OCFS2 filesystem. If you do both, you will have to install both. ASM has some interesting "storage" like features, for example extended clusters and online disk reorganization. You can do some of these with OCFS2. For example, adding a disk. But try to remove a OCFS2 volume with the database online and not disrupt your users. ASM can do that. On the other hand ASM is less transparent. You have little control on how the data is layout, and the only tool to manage files is a ftp like client, that you need to use to delete dangling files or if you need to backup something manually. Database backups would usually need to go through RMAN. On OCFS2 you can use standard operating system commands to manage the datafiles. ASM also has no recovery tools, like fsck. Regards, Luis --- On Mon, 2/9/09, Karim Alkhayer <kkha...@gmail.com> wrote: From: Karim Alkhayer <kkha...@gmail.com> Subject: RE: [Ocfs2-users] ASM over OCFS2 vs. Standard locally managed tablespaces To: lfreita...@yahoo.com, ocfs2-users@oss.oracle.com Date: Monday, February 9, 2009, 10:47 AM We’re using OCFS2 for RAC on top of SLES9, which we’re going to upgrade to SLES10. Around 10 TB RAID6 multi disk arrays, 5 databases on RAC, and 5 single instances standby for the primary site As there is no AI component in ASM to detect the fast LUNs, and RAC on SLES requires a shared file system. Therefore, on a set of identical LUNs, in terms of capacity and speed, ASM should take care of distributing the balance over LUNs, and OCFS2 is expected to work even better if these LUNs are placed on several disk groups (arrays) How would this scenario (ASM over OCFS2) work? What are the cons and pros? Keep in mind that the goal of such a concept is provide performance and reliability with the least possible administration Appreciate your thoughts Best regards, Karim From: ocfs2-users-boun...@oss.oracle.com [mailto:ocfs2-users-boun...@oss.oracle.com] On Behalf Of Luis Freitas Sent: Monday, February 09, 2009 2:16 PM To: <ocfs2-users@oss.oracle.com> Subject: Re: [Ocfs2-users] ASM over OCFS2 vs. Standard locally managed tablespaces Karim, I dont see why run ASM over OCFS2. It seems to be a useless overhead. Either you run ASM or OCFS2. Btw, neither ASM nor OCFS2 are smart enough to detect that some LUNs are faster than others. ASM expects each diskgroup to be comprised of LUNs of similar performance in order for it's load balancing algorithms to work. OCFS2, as far as I know doesnt have this type of management built in. See: http://www.oracle.com/technology/products/database/asm/pdf/take%20the%20guesswork%20out%20of%20db%20tuning%2001-06.pdf Section: ASM Best practices and principals. About the performance, ASM is said to have similar performance to raw devices in a SAME layout, being tightly integrated to Oracle. OCFS2 has some overheads that are inherent to a file system, like cache management, locking, context switching, so it is likely to use more CPU power than ASM. But I dont remember any specific benchmark comparing those. Also, keep in mind that when you use a filesystem you are using part of the memory for the filesystem cache. When using RAW or ASM you would need to allocate this memory to the block buffer in order to compare results. Regards, Luis > Hello All, > > > > Are there any benchmarks with respect to performance with respect to > ASM over OCFS2 vs. standard locally managed tablespaces? > > In our environment, data files hosting tables/lobs are stored on a > RAID6 disk array with 10K rpm disks, whilst indices are stored on a > different RAID6 disk array with 15K rpm disks. > > We’re using oracle managed files for the rollback/undo and temporary > tablespaces. > > Would ASM over OCFS2 be smart enough to detect the fast LUNs? > > > > Appreciate your thoughts. > > > > Best regards, > > Karim > > _______________________________________________ > Ocfs2-users mailing list > Ocfs2-users@oss.oracle.com > http://oss.oracle.com/mailman/listinfo/ocfs2-users _______________________________________________ Ocfs2-users mailing list Ocfs2-users@oss.oracle.com http://oss.oracle.com/mailman/listinfo/ocfs2-users
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