New features in General Purpose and optimized Cloud Servers
This article describes some of the major features and benefits of the General Purpose and work-optimized flavors (configurations) of Cloud Servers compared to Standard servers.
The newer flavors use faster solid state drives (SSD) and separate the system disk from the data disk, with both disks equally RAID 10 protected. With your operating system on a separate disk from your data, you can more easily create an image of the system disk because it is a fixed size and doesn't scale up as other resources increase. For more information on data disk imaging limitations, see Images Capture System Disk Only (below) or for the full procedure,see Create an image of a server and restore a server from a saved image. You can back up the data on your data disk or disks by leveraging either Rackspace Cloud Backup or Rackspace Cloud Block Storage (an option that can also be used to increase the storage capacity of your server, if needed). For a comparison of the two data disk backup options, see Best Practices for Backing Up Your Data: Cloud Block Storage versus Cloud Backup.
Faster Server Provisioning
Dedicated 10-gigabit Ethernet (10 GigE) for networking on the host computer, SSDs, and no requirement to format the entire disk (system disk only) when building your servers will make the time to provision noticeably quicker.
Higher Memory Availability
The newer flavors are available with RAM selection of up to 120 GB per server (up from 30 GB in the Standard server class).
The newer flavors provide more processing power: up to 32 vCPUs or virtual cores (compared to a maximum 8 vCPUs on the largest-size server in the Standard server class). For information, see Optimized server types.
General Purpose Servers provide more network bandwidth: 40 gigabit Ethernet (40 GigE) to each host server (the physical machine that houses your virtual server). Each host server gets 20 GigE for management and Cloud Block Storage, and 20 GigE for the server's public network, ServiceNet, and network traffic. This bandwidth dramatically improves the interoperability of the newer flavors with complementary services such as Cloud Block Storage over the Standard server class.
Higher Maximum IOPS
Separating the operating system from the data provides higher maximum input/output operations per second (IOPS). For example, the 1 GB General Purpose flavor with 20 GB of system disk and no data disk can process about 20k IOPS. The 120 GB I/O optimized flavor with a 40 GB system disk and 1200 (or 4x300) GB data disks can perform about 80k IOPS. Compare this with the General Purpose server class for Cloud Servers, which can only process approximately 2k IOPS.
I/O optimized servers are assigned networking resources and use local high-speed SSD drives for storage. I/O optimized servers work best for applications that require frequent or sustained disk access, like databases.
Compute optimized servers have a high CPU allocation to optimize the server for applications with high CPU demands, like web servers and application servers. All disk storage for Compute optimized servers is on Cloud Block Storage.
Memory optimized servers have larger allocations of low-latency RAM for memory-intensive applications like caching servers, in-memory analytics, and search indexes. All disk storage for Memory optimized servers is on Cloud Block Storage.
What Is different between the new flavors and Standard flavors?
Changes have been implemented with General Purpose servers to align with industry standards, improve server imaging and consistently allocate adequate disk resources for each server.
One of the biggest differences between the Standard servers and the newer flavors is that the newer flavors cannot dynamically resize. With the rest of the OpenStack community, Rackspace is reducing support for this feature because it does not align with the industry-standard method of scaling. Rather than resize one server for vertical scaling, we instead recommend employing horizontal scaling, adding or removing the number of servers managed by a load balancer, to manage your available resources to suit your needs. For information on changing your General Purpose Server's size, see Changing the Size of Your General Purpose or optimized Cloud Server.
Images of your system capture only your operating system's configuration (your system disk). This makes the imaging process run more quickly and reliably without placing undue strain on your server. To retain the information stored on attached data disks for General Purpose and I/O optimized flavors, you can use Cloud Block Storage or Rackspace Cloud Backup to save only the files and directories that you need. For a comparison of the two options, see Best Practices for Backing Up Your Data: Cloud Block Storage versus Cloud Backup.
Preparing the Data Disk For Use
As a result of having a separate System Disk and Data Disk with General Purpose and I/O optimized Servers, you will need to prepare your data disk by formatting and mounting it to your server before you can use it. Please follow the instructions in these articles to prepare your data disk for use:
No 512 MB RAM Servers
The 512 MB RAM cloud server is not available for the newer Cloud Servers flavors. As a server that uses shared CPU and networking resources, maintaining the 512 MB size would place too much stress on the host because of the bursting capabilities, and potentially negatively impact other servers on the host computer.
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