Oracle Critical Patch Update or CPU is a collection of patches for multiple security vulnerabilities across all Oracle product lines. The details of the CPU have been announced prior to the actual release of the patches for the first time ever starting this year. The CPU is scheduled to release every quarterly, on January, April, July and October each year.
Oracle makes two efforts to ease the patching process - Pre-Release Announcement and CVSS Risk Matrix. The Common Vulnerability Scoring System is a vendor agnostic, industry open standard designed to convey vulnerability severity and help determine urgency and priority of response.
The ability to score information system vulnerabilities is extremely important to the professional computing world. CVSS provides the foundation for a standard process for stakeholders to prioritize their actions and respond to the threat vulnerabilities present. Vulnerabilities with a CVSS base score of 0.0 represent problems that are not exploitable in a default database environment. The higher the base score the greater the severity of the vulnerability.
The new Oracle 11g database has 482 new features, cutting across such areas such as manageability, high availability, scalability, content management, infrastructure and business intelligence. The key theme of 11g is to provide “change assurance”. The following is a glimpse of a subset of all the new features:
- Compression technology that can reduce the amount of storage required for data sets by up to two thirds
- Speed boost allowing Oracle to finally beat file systems on reading data
- Data Guard - the ability to create a standby snapshot for the purpose of regression testing and to keep it in sync with your production database
- Replay Workload - the ability to capture all (or just SQL) database activities and then moving it to a testing environment without using a midtier tool
- Online Application Upgrades - hot patching, the ability to install upgrades or patches online with no downtime
- Quick Fault Resolution - the ability to capture of all diagnostics related to a fault automatically
- Database Repair Advisor - a wizard/expert system that guides DBAs through the fault diagnosis and resolution process
- Partition by logical object and automated partition creation to help manage Very Large Databases (VLDBs)
- New high-performance Large Objects (LOB) infrastructure
- Native Java & PL/SQL compilers
- Re-engineered driver for PHP
via OTN TechBlog
Jeffrey Hunter has published an insightful article about building an Oracle RAC 10g R2 Cluster with less than $1,800. If you are struggling to maintain an Oracle RAC at your work, do take a look. The system involved comprises a dual-node cluster (each with a single processor) running Linux (CentOS 4.2 or Red Hat Enterprise Linux 4) with a shared disk storage based on IEEE1394 (FireWire) drive technology.
Large sequential I/O can cause performance problems due to excessive use of the memory page cache. One way to avoid this problem is to use direct I/O on filesystems where large sequential I/Os are common. Direct I/O is a mechanism for bypassing the memory page cache alltogether.
DIRECTIO_ON allows you to force directio per-file and is used by Oracle database. The idea is that with a properly sized memory area the database can manage its own buffering and avoid the overhead of copying to kernel buffers. Even after the database is shut down directio will persist for a long time. The flag is set in the inode’s i_flag and hangs around cached within the inode in the DNLC and will effect files until the inode is flushed from the DNLC.
John Alderson demonstrated the problem using two simple C programs.