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分类: 服务器与存储

2008-08-22 09:57:59

VCS enhances the performance of IBM AIX environments.
Such a claim only carries meaning when it is backed up with industry-standard testing and
performance benchmarks. VERITAS cannot provide such information.
It is true that VERITAS provides internal data (“TPC-like”) that, under certain circumstances,
shows it can achieve 99% of, or even exceed the performance of, a raw disk I/O environment
(Oracle and DB2 VCS versions) while still offering the obvious administrative ease benefits of a file
system. VERITAS accomplishes this through its database accelerator (e.g., Quick I/O, Cached
Quick I/O) and other software.
Under certain conditions, this claim has validity but it is application- and environment-dependent
and often only applies in limited circumstances depending on database size, memory size,
application, buffer pool, etc. Moreover, the performance increase is only a small part of what
determines overall system performance. In any case, IBM technology can provide comparable
results in most scenarios. For example, IBM DB2’s memory map I/O feature for AIX (using IBM’s
JFS), can also offer raw disk-like performance. Every environment will achieve different results from
both VERITAS and IBM when raw disk-like performance is attempted while running a file system.
VERITAS agents remove the need for scripts. Moreover, agents manage the complete AIX
environment particularly well for disaster recovery or other kinds of failure. These agents are
integrated into the VCS environment for ease-of-use, and out-of-the-box capability.
Scripts provide great functionality that can be comparable or superior to agents and IBM provides
aid in writing these scripts. Moreover, IBM HACMP software in combination with tightly coupled
AIX scripts provides similar functionality to the VERITAS embedded and enterprise agents. Finally,
HACMP is part of an IBM product set that also manages the complete environment.
VERITAS provides dynamic multipathing to address failures (through its Volume Manager).
HACMP and AIX provide the same functionality. Dynamic multipathing is not unique and other
vendors can also accomplish it.
VERITAS can provide replication through server software that comprehends different vendors’
storage, rather than through the storage array, which must be the same on both ends of the cluster.
This eliminates the need for special storage hardware.
Storage-based replication (asynchronous or synchronous) remains the industry standard and the
implementation of server-based synchronous replication usually causes a decrease in server
performance. In any case, the VERITAS solution remains to be proven in many environments.
VCS runs on Microsoft Windows, Sun Solaris, HP’s HP-UX, Linux, and IBM’s AIX. IBM’s
HACMP only runs on IBM’s AIX.
The VERITAS claim is correct but misleading. It is true that IBM’s HACMP is designed for IBM’s
AIX, just as Sun’s and HP’s clustering software are designed for their respective operating systems.
In this way, the clustering software is optimized for the particular environment at hand and can take
advantage of tight coupling into the operating system as well as hardware feature comprehension to
make best use of the operating system features. VCS is a general-purpose clustering software
offering and must work to accommodate all the operating systems it functions with. This approach
entails compromise. For the IBM environment, HACMP is the optimum choice.
VCS works with, and is tightly integrated with, a host of other VERITAS products such as Global
Cluster Manager, Cluster Server QuickStart, Database Edition/Advanced Cluster for Oracle or
DB2, Cluster Server Traffic Director, Volume Manager, Cluster File System, netBackup, and
Volume Replicator. This provides a superior environment for AIX clusters.
IBM offers specific products (e.g., from IBM Tivoli) that match or exceed the functionality of all the
mentioned VERITAS products. Moreover, the system administrator can provide the equivalent of
all the mentioned functionality by use of the software and tools IBM provides. This approach also
results in an integrated set of capabilities, which uniquely meets the needs of the AIX environment.
This is accomplished without the need for a “lowest common denominator” approach, which
accommodates the products of other vendors besides IBM.
VERITAS supports the popular Oracle9i Real Application Clusters (RAC).
RAC is also fully supported in HACMP configurations. In fact, all major cluster vendors support the
popular Oracle RAC software.
VERITAS allows AIX clusters to use 10 MBs, 100 MBs, and Gigabit Ethernet for network
Not only does IBM’s HACMP allow all three popular Ethernet network connection speeds, it also
allows ATM, FDDI, token-ring, and the industry-unique SP switches (SP and SP2), which provide
the ultimate in throughput. In fact, VERITAS is trying to turn a deficiency into a feature since its
proprietary protocol is limited in what network connectivity it can support.
VCS supports SCSI and Fibre Channel disk connectivity as well as IBM’s proprietary SSA
IBM also supports these disk connectivity techniques. Since SSA is a popular IBM disk product for
clusters, how could VERITAS not support it for clusters if it wants to be in the HACMP-AIX
VERITAS provides an easy-to-use Java-based GUI for management of VERITAS environments. It
also provides a CLI for deep drill-down.
IBM also supports web-based management interfaces such as WebSM, as well as a CLI and the IBM
standard SMIT menu system.
VCS provides predefined resource and application agents for the AIX environment to ease
IBM offers superior monitoring/alert capabilities via RSCT Resource Monitors. HACMP includes
numerous resource monitors that may be used to trigger various actions in response to changes in
thresholds. Customers and ISVs may develop application- and resource-specific Resource Monitors.
Furthermore, HACMP provides a simple means to associate recovery actions with AIX Error Log
entries. This allows a broad range of conditions to be monitored without requiring Resource
Monitors. In short, resource management is integrated into the logic of HACMP. As far as
application agents are concerned, sample application scripts are available from IBM for free
download. The system administrator needing optimum performance of his or her environment
customizes these scripts to the environment at hand.
VERITAS is the industry’s number one UNIX system high-availability solution.
The number of licenses VERITAS has sold for the AIX environment is unknown. In contrast, it is
known that IBM has sold more than 55,000 HACMP licenses to more than 25,000 customers.
VERITAS products allow cross-platform cluster management for eased system administration.
This claim is correct and is based on VERITAS’s business philosophy to manage the clusters of all
the major vendors. Note that the nodes in a managed cluster must be homogeneous. HACMP does
not address this kind of multi-vendor environment, so while the claim is correct, it is not relevant to
the AIX environment.
VCS allows resource and service groups to fail over as an entity, as required.
HACMP provides the same functionality.
VCS allows both IP address takeover and the local swapping of IP addresses.
HACMP provides the same capability, as do most clusters, since this is a standard capability.
VCS allows the definition of resource relationships, and the relationships between resources and
service groups.
Most resource relationships are built into the HACMP software. Less commonly used relationships
can be scripted as needed. Similarly, it is possible to define many resource and service group
relationships through HACMP scripting. Functionality similar to what VERITAS offers is achieved.
VCS is integrated with VERITAS netBackup backup/recovery software.
HACMP for AIX is integrated with Tivoli Storage Manager for backup/recovery.
VCS is integrated with VERITAS Volume Replicator and Global Cluster Server.
HACMP is integrated with IBM’s HAGEO software, so there is comparable functionality.
VCS allows more user security for administrative tasks than HACMP since it allows multiple user
level security.
HACMP also allows user level security for administration based on AIX’s support for role-based
security. Comparable functionality is thereby provided; it is only the implementation that is different.
VCS for AIX allows the addition and removal of nodes without taking down the cluster, allows the
starting and stopping of the cluster without taking the application down, and allows the
administrator to halt an individual component of a resource or a service group.
HACMP also allows the addition and removal of nodes without taking down the cluster, and allows
the starting and stopping of the cluster without taking the application down. It is true that individual
resource or service group components cannot be stopped – the group must be stopped. The need
for this granularity is situation dependent and IBM would provide it if there were demand.
VCS can decide which node to fail over to based on the node load.
IBM also provides this capability. Moreover, IBM’s RSCT allows a number of different ways to
define “load” so that the system administrator has multiple choices and can choose the best
VERITAS is sold by IBM Global Services thus showing its value even to IBM.
Many products from many vendors are sold by IBM Global Services. In the case of VERITAS,
these sales are most often only made when Global Services needs to accommodate a multi-vendor
cluster environment and the customer wants a single vendor for all the different cluster types to be
managed. There are also some cases where VERITAS disaster recovery software is best for the
customer (e.g., depending on the kind of storage available or desired).
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