We have several Oracle server on RH 6.6 and 5.x Oracle has said we should use xfs over ext4.
Also any docs on how to define/mount xfs.
I am assuming you use the mkfs -t xfs /dev/vgname/lvname

Can you give me some info on one vs the other ? pros and cons etc.
A comparison document would be nice.

From Oracle docs :
mkfs If you have used the "Disk Utility" to create your partitions, or they were created during the installation by "Disk Druid", they will already be formatted with a file system, so this step will be unnecessary. Once you have created a suitable partition, it is likely you will want to create a file system on it. This can be done using one of the variations of the mkfs command. There are a wide variety of file system types available, but the Red Hat certification exams only consider ext2, ext3 and ext4. The ext4 file system is the default for RHEL6, so I will focus on that. The mkfs command destroys any data on the partition, so be very careful when issuing the command. The following three commands all format and ext4 file system on the specified partition. # mkfs.ext4 /dev/sdb3 # mkfs -t ext4 /dev/sdb3 # mke2fs -t ext4 /dev/sdb3 Not surprisingly, to create an ext2 or ext3 file system simply replace ext4 in the above commands. Although not required for the certification exam, the xfs file system is quite important for single instance Oracle installations. If you are storing datafiles on a cooked file system, as opposed to ASM, you should probably consider using xfs, rather than any of the ext* file systems.

Part 2 of the question:

Also they are requesting these setting: with Standard mount options New mount options Oracle bin and shared libraries mount -o rw
Cached by AIX mount -o rw
Cached by AIX Oracle Datafiles mount -o rw
Cached by Oracle Cached by AIX mount -o rw
Cached by Oracle *Use filesystemio_options to configure *cio Oracle Redolog mount -o rw
Cached by Oracle Cached by AIX mount -o (jfs2 + agblksize=512)
Cached by Oracle Oracle Archivelog mount -o rw
Cached by AIX mount -o rbrw Use JFS2 write-behind … but are not kept in AIX Cache.
Oracle Control Files mount -o rw
Cached by AIX mount -o rw Cached by AIX *(1) : to avoid demoted IO : jfs2 agblksize = Oracle DB block

Does RH have these settings? How are they set? In the fstab?

We pretty much use ext4 on RHEL5/RHEL6.

You can use mkfs.ext4 as a shortcut for making ext4 filesystems.

Type "man mkfs.ext4" for details.

For the binaries filesystem we just use the defaults for ext4 in /etc/fstab:
/dev/VGORA/lvdevora /oracle/dev ext4 defaults 1 3
The above mounts our logical volume lvdevora in volume group VGORA on mountpoint directory /oracle/dev. It specifies it as ext4 and says to use defaults for that filesystem type. The remaining two numbers deal with priority and order.
See "man fstab" for more details.

For database filesystems we use slightly different options rather than defaults:
/dev/VGORA/lvdevdata01 /database/devdata01 ext4 noatime,nodiratime,_netdev 1 3


The "-o rw" is available in RHEL but by default mounts ARE read/write so no need to specify it. (It is more usual to see "-o ro" for readonly if you had a filesystem you did NOT want to read/write.)

Of course the above assumes you're doing filesystems rather than using Oracle's ASM which has its own way of doing things. (ASM used often if you want to do Oracle RAC/GRID clustering.)

I'd suggest you peruse Oracle documents related to RHEL and/or OEL (Oracle Unbreakable Linux) as the latter is Oracles fork from RHEL. It will be more relevant than documents aimed at AIX which is IBM's UNIX variant. The LVM in Linux may not be exactly the same as AIX even if there are similarities.

Thank you for the info.
I do support AIX as well as red Hat Linux. My DBA was comparing the 2 systems. Apples to oranges as it were.

My DBA is checking with Oracle too to see what else he can find out.
I appreciate the inf you provided as I am not versed in Oracle but the OS only.
I will check into the mkfs.ext4 command as well I usually use the mkfs -t ext4 command.

I can see we have some research to do before we change. I don't understand why Oracle is saying to use XFS. I have not used it before.
Yes google is my friend too.

In what you quoted from Oracle Docs it says:
Where are you getting anything saying it has to be XFS?

From the doc the dba provided to me.

the xfs file system is quite important for single instance Oracle installations. If you are storing datafiles on a cooked file system, as opposed to ASM, you should probably consider using xfs, rather than any of the ext* file systems.

That surely doesn't sound like a "requirement". As I noted we run Oracle DBs for the most part on Linux on ext4 and previously on ext3. (In early versions of RHEL5 ext4 was not fully supported - we switched to ext4 once it was and also continue to use it on RHEL6.) A couple of reasons ext4 is better than ext3:
1) fsck on ext3 took forever on large filesystems like those we used for databases. For the most part we had used tune2fs to turn off automatic checks at boot because it would periodically do automatic fsck. On ext4 the boot check runs quickly so doesn't interfere with bringing up the system.
2) For some reason deleting files from some ext3 filesystems took a long time. This caused issues if we were doing a database refresh to a test/dev DB by first deleting older datafiles then copying in newer ones form production. Not an issue in ext4.

We run multiple databases including Oracle ERP, History Database and Data Warehouse all on ext4 with no problem. We do also run some smaller databases on a RAC/GRID cluster so use ASM there but all of our large ones are on ext4.

The only reason I'd consider going to xfs is if I was nearly or exceeding the limits of ext4.

Agreed but have you met a DBA when they get hold of something they don't let go. Just because Oracle said does not mean we should do it.

That is the reason I am asking here. I also found out xfs is a purchased product in Rhel.
Don't know the pricing says see your sales team.

In most organizations cost gets trumped by free. Just tell your DBA all he has to do is write the proposal for purchase and you'll gladly install and use it once management has done the purchase. Even if he is willing that process is usually not going to be fast and he might give up for expediency.

By the way you might want to do you own searches on Oracle's site and the internet regarding use of ext4 for the specific product. My experience is that DBAs have a tendency to stop at the first link or the one that "proves" their worldview and ignore all others.

DBAs are lovely in that they will look at any Oracle error code discussion, see 15 possible causes all of which they'll ignore in favor of the 2 at the bottom of the list which are general "you may have an OS issue" or "you may have a hardware issue". They'll then expect you to spend the next week "proving" there is no OS or hardware issue before they'll actually look at the more likely causes.

I think we convinced them to use ext4 for now. Rhel 7 they include xfs as part of the OS.

Honestly, your DBA needs to look hard at what they're doing. ASM is by far the better way to do this.
So, contact your RHEL sales team for pricing, then.

Only if you're doing RAC/GRID where it is required. Oracle databases run fine on cooked filesystems.

Since ASMLIB isn't available without building your own on RHEL6 (and probably RHEL7) using ASM takes some extra effort as Oracle documentation assumes use of ASMLIB (which they build for OEL but not for RHEL after RHEL5). Also if you use ASM the chances your DBA will muck with it is heightened. Some can't seem to get the idea that ASM does NOT have to spread across the fiber attached storage you provide since it is already spread in the RAID LUNs.

Absolutely, but for a DBA to *INSIST* on avoiding ASM is kind of odd.
Yes...the DBA mucking with things is my favorite kind of problem: SOMEONE ELSES.

Hi @unix1adm,

I'm in the same situation looking for similar linux filesytem options for agblksize=512 of AIX for redolog filesystems.
Did you find anything foe this, any updates from oracle, please let us know how you solved this and suggestions.

Thank you.

Hi no I never got an answer to the –a agblksize=512 question.

We are not using it and it seems not to cause any issued. But I would like to know how to do it.

...and....
Did either of you try to look this up? This is extensively documented in the Oracle documentation. The agblksize is an option you set when you create the file system.

Try reading the man pages for crfs and mkfs.