Specifications
Data Replication
Description
32-bit zlib packages should be installed to RHEL 6 (64-bit) for Set Compression Level
When using SDR with RHEL 6 (64-bit), the following error may appear:
Could not start balance on Target when Compression Level is set on RHEL 6 (64-bit)
Solution: To resolve the issue, please install the 32-bit zlib packages from RHEL 6 when using
RHEL 6 (64-bit).
Mirror breaks and fills up /var/log/messages with errors
This issue has been seen occasionally (on Red Hat EL 6.x and CentOS 6) during stress tests with
induced failures, especially in killing the nbd_server process that runs on a mirror target system.
Upgrading to the latest kernel for your distribution may help lower the risk of seeing this particular
issue, such as kernel-2.6.32-131.17.1.el6 on Red Hat EL 6.0 or 6.1. Rebooting the source system
will clear up this issue.
With the default kernel that comes with CentOS 6 (2.6.32-71.el6), this issue may occur much more
frequently (even when the mirror is just under a heavy load.) Unfortunately, CentOS has not yet
released a kernel (2.6.32-131.17.1) that will improve this situation. SIOS recommends updating to
the 2.6.32-131.17.1 kernel as soon as it becomes available for CentOS 6.
Note: Beginning with SPS 8.1, when performing a kernel upgrade on RedHat Enterprise Linux
systems, it is no longer a requirement that the setup script (./setup) from the installation image
be rerun. Modules should be automatically available to the upgraded kernel without any intervention
as long as the kernel was installed from a proper RedHat package (rpm file).
High CPU usage reported by top for md_raid1 process with large mirror sizes
With the mdX_raid1 process (with X representing the mirror number), high CPU usage as
reported by top can be seen on some OSdistributions when working with very large mirrors (500GB
or more).
Solution: To reduce the CPU usage percent, modify the chunk size to 1024 via the LifeKeeper
tunable LKDR_CHUNK_SIZE then delete and recreate the mirror in order to use this new setting.
The use of lkbackup with DataKeeper resources requires a full resync
Although lkbackup will save the instance and mirror_info files, it is best practice to
perform a full resync of DataKeeper mirrors after a restore from lkbackup as the status of source
and target cannot be guaranteed while a resource does not exist.
232Troubleshooting