Dude wrote:Yes, however...
Now that Oracle Linux 6 has been certified for Oracle 11gR2, does this also include the use of the ext4 file system?
I'm asking because I found database performance and block corruption warnings searching in Google, but perhaps this only applied to early implementations of ext4 or were simply wrong assertions. I imagine that certification includes ext4, but just to be sure, is there still a reason to be concerned about it?Performance is still an issue, and for that reason alone we strongly recommend ASM for database storage. We will be releasing oracleasmlib for OL6 soon, so I would wait for that. You might also want to compare the performance of ext4 and XFS for your database storage, as I find XFS to perform much better for MySQL and PostgreSQL storage on OL6. I haven't used ext3/4 for database storage for years.
Avi Miller wrote:Having said that, ASM is still our preferred, recommended option with the best support from the DB and Linux teams.
You might also want to compare the performance of ext4 and XFS for your database storage, as I find XFS to perform much better for MySQL and PostgreSQL storage on OL6. I haven't used ext3/4 for database storage for years.
Dude wrote:It's not file-based redundancy. ASM does full load-balancing/levelling and N-level striping across all the devices you provide to the ASM group. Also, with the introduction of Grid Infrastructure, it's no longer a full separate database instance. I strongly recommend you give ASM a go. It's pretty simple, even I can do it. :)
ASM has very interesting features and I like its concept of file based redundancy, as opposed to the usual RAID concepts found with other solutions. However, it requires another separate database instance and has it's own learning curve.
How about UEK2 and setting up a partition using btrfs for Oracle tablespace and operational files?btrfs in its default mode is not at all suited to database workloads. You may want to disable the datacow option (nodatacow) on mount for some semblance of performance.
Dude wrote:It supports concurrent reads, not writes so if you're running a warehouse type database where it's mostly reads, you'd be fine but if you're doing a lot of writes, you should consider other options (assuming you care about latency and performance).
Concurrent I/O seems to be a topic often discussed when comparing XFS with ext4. If I'm not mistaken then ext4 supports concurrent I/O, but there is a performance penalty compared to XFS, i.e. fragmentation. However, I have not found any information outlining that this was a new issue introduced with ext4.
Apparently people are storing Oracle datafiles under ext3 without problems. The ext4 filesystem is the successor of ext3 and ext2, providing more features and robustness. How performance issues of Oracle DB pertain to ext4 is probably subject to errata and updates.
From what I can gather, ASM (ACFS), or OCFS2 in a RAC environment are the best options under Linux. Performance results will also depend on the underlying storage technology, for instance, caching, SSD or conventional rotary devices.