User`s guide

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• If you use the -s option to specify a sector size to mkfs.btrfs that is different from the page size, the
created file system cannot be mounted. By default, the sector size is set to be the same as the page
size. (Bug ID 17087232)
CPU microcode update failures on PVM or PVHVM guests
When running Oracle Linux 6 with UEK R3, you might see error messages in dmesg or /var/log/
messages similar to this one:
microcode: CPU0 update to revision 0x6b failed.
You can ignore this warning. You do not need to upgrade the microcode for virtual CPUs as presented to
the guest. (Bug ID 12576264, 13782843)
DHCP lease is not obtained at boot time
If DHCP lease negotiation takes more than 5 seconds at boot time, the following message is displayed:
ethX: failed. No link present. Check cable?
If the ethtool ethX command confirms that the interface is present, edit /etc/sysconfig/network-
scripts/ifcfg-ethX and set LINKDELAY=N, where N is a value greater than 5 seconds (for example,
30 seconds). Alternatively, use NetworkManager to configure the interface. (Bug ID 16620177)
dm-nfs obsoleted
In UEK R2, the dm-nfs module provided the ability to create a loopback device for a mounted NFS file or
file system. For example, the feature allowed you to create the shared storage for an Oracle 3 VM cluster
on an NFS file system. The dm-nfs module provided direct I/O to the server and bypassed the loop
driver to avoid an additional level of page caching. The dm-nfs module is not provided with UEK R3.
The loop driver can now provide the same I/O functionality as dm-nfs by extending the AIO interface to
perform direct I/O. To create the loopback device, use the losetup command instead of dmsetup.
DTrace
• Using kill -9 to terminate dtrace can leave breakpoints outstanding in processes being traced,
which might sooner or later kill them.
• Argument declarations for probe definitions cannot be declared with derived types such as enum,
struct, or union.
• The following compiler warning can be ignored for probe definition arguments of type string (which is a
D type but not a C type):
provider_def.h:line#: warning: parameter names (without types) in function declaration
ERST message
You can safely ignore the following message that might be displayed in syslog or dmesg:
ERST: Failed to get Error Log Address Range.
The message indicates that the system BIOS does not support an Error Record Serialization Table
(ERST). (Bug ID 17034576)
ext4 inline data
The inline data feature that allows the data of small files to be stored inside their inodes is not yet available.
The -O inline_data option to the mkfs.ext4 and tune2fs commands is not supported. (Bug ID
17210654)