What is the difference between the 'Disaster Recovery' and 'Full' versions of ZXTM GLB?
ZXTM Global Load Balancer provides two capabilities:
- Business Continuity enables failover from one datacenter to another in the event of datacenter failure, so that the service is available despite the datacenter failure
- Improving Customer Experience is achieved by load-balancing users across multiple datacenters simultaneously, depending on datacenter performance and geographic proximity.
The 'Disaster Recovery' version of ZXTM GLB only provides the business continuity capability. It directs all users of a service to the same datacenter unless that datacenter fails.
The 'Full' version of ZXTM GLB also load-balances users across multiple active datacenters to give them the best possible level of service by minimising the transaction latency.
How many ZXTM GLB devices are required?
There must be at least one ZXTM GLB device located in each datacenter that is hosting a service. The ZXTM GLB device monitors the health and performance of the services in the local datacenter, and exchanges this information with the ZXTM GLB devices in other datacenters. This way, every ZXTM GLB has an accurate impression of the availability and performance of every datacenter.
A single ZXTM GLB in a datacenter creates a single point of failure for that datacenter. If the ZXTM GLB were to fail (because of a hardware fault for example), then the datacenter would not broadcast health information and the other ZXTM GLB devices would consider it as failed. It is common to run a pair of ZXTM GLB devices in each datacenter to elinimate this single point of failure.
How accurate is the GeoIP information that ZXTM GLB uses?
ZXTM GLB uses a database of IP address to geographic location when performing geographic load balancing and on the global map visualization. This database is 100% accurate per country, and over 60% accurate per city within a country. Users can manually extend the database, giving specific geographic locations to IP blocks if required.
What are the different delivery platforms for ZXTM GLB?
ZXTM GLB is available as software for a range of operating systems and server types:
Platform Fully Supported OS version Linux x86 2.6.8+ Linux x86-64 2.6.8+ FreeBSD 5.3+, 6.1+ Solaris SPARC 8, 9, 10 Solaris x86 10 Solaris x86-64 10
It is also available as a complete appliance on Zeus' 2000 and 7000 appliances. The 7000 appliance is more powerful, with redundant (fault-toleranct) disks and power supply units.
How many DNS requests can ZXTM GLB process?
A server equipped with a single Opteron processor and can manage and rewrite over 30,000 DNS requests per second. A two-core or dual Opteron system and can manage and rewrite over 40,000 DNS requests per second.
When ZXTM GLB devices are deployed in a cluster, DNS traffic is shared between then using round-robin DNS. So, a cluster of 4 ZXTM GLB systems could handle over 100,000 DNS requests per second.
ZXTM GLB can modify the TTL field in DNS responses, giving you control over how frequently clients re-request DNS data.
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