We use the same environment we installed here which consists of two virtual machines running Oracle Enterprise Linux 5 Update 3 64-bit with Oracle 11g Release 2 (Grid Infrastructure and Oracle binaries) installed. All data is placed in ASM with normal redundancy. Storage is exported from two Netapp Filers via iSCSI.
Writing posts for this blog i wondered: Am i allowed to post Metalink Notes entirely or partially in my blog posts?
Looking at the web i did not find any information. I might have read the Oracle Support License but due to lengthiness – and because i am not a lawyer i refused from this :-)
So i opened a SR and asked my question. This is the reply i got:
The customer can refer to Document IDs in My Oracle Support, but is NOT allowed to reproduce any Support content which currently requires a login to Oracle Support, doing so would violate the terms of their Oracle Support License.
I guess that answers the question entirely.
Users running Oracle on Red Hat or Oracle Enterprise Linux will most probaly use ext3 as default file system. It is robust, well maintained, a journaling file system and supports file system sizes up to 32 TB.
Database servers must be “high available” – so they are booted infrequently if ever.
Even if ext3 is a journaling file system there are periodic full file system checks which will check the entire file system just like ext2 did after a crash. On todays large file systems this can take hours. Thats especially bad if you just “quickly” rebooted the server after applying a patch and now facing a long running file system check.
Many users complained about this behavior and said ext3 is a journaling file system and should be running without periodic checks. On the other hand this is a security feature. Even with journaling corruptions may be introduced and remain undetected for a long time.
So lets take a look at the defaults chosen on Oracle Enterprise Linux 5 Update 3 when creating a ext3 file system:
[root@rac1 ~]# mkfs.ext3 /dev/asm/testvol1-132 mke2fs 1.39 (29-May-2006) Filesystem label= OS type: Linux Block size=4096 (log=2) Fragment size=4096 (log=2) 131072 inodes, 262144 blocks 13107 blocks (5.00%) reserved for the super user First data block=0 Maximum filesystem blocks=268435456 8 block groups 32768 blocks per group, 32768 fragments per group 16384 inodes per group Superblock backups stored on blocks: 32768, 98304, 163840, 229376 Writing inode tables: done Creating journal (8192 blocks): done Writing superblocks and filesystem accounting information: done This filesystem will be automatically checked every 22 mounts or 180 days, whichever comes first. Use tune2fs -c or -i to override.
The last two lines are the ones of interest: “The file system will be checked every 22 mounts or 180 days, whichever comes first”. On database serverss 22 mounts seems a long time but 180 days are quite short. So administrators should change these values accordingly. Turning it off completely is a loss of data protection but still possible.
You can check the mount counts, maximum mount counts and check intervals with the following command:
tune2fs -l /dev/asm/testvol1-132 [..] Mount count: 0 Maximum mount count: 22 [..] Last checked: Thu Oct 1 10:44:53 2009 Check interval: 15552000 (6 months) Next check after: Tue Mar 30 10:44:53 2010
You are free to change these values with tune2fs:
[root@rac1 ~]# tune2fs -c 100 /dev/asm/testvol1-132 tune2fs 1.39 (29-May-2006) Setting maximal mount count to 100 [root@rac1 ~]# tune2fs -i 360 /dev/asm/testvol1-132 tune2fs 1.39 (29-May-2006) Setting interval between checks to 31104000 seconds
…verifying:
tune2fs -l /dev/asm/testvol1-132 Filesystem created: Thu Oct 1 10:44:53 2009 Last mount time: n/a Last write time: Thu Oct 1 11:02:09 2009 Mount count: 0 Maximum mount count: 100 Last checked: Thu Oct 1 10:44:53 2009 Check interval: 31104000 (12 months) Next check after: Sun Sep 26 10:44:53 2010
So based on this information:
The actual values depend completely on your requirements. But they should be set completely different for different volumes. This will prevent a full check on all your volumes at once.
