In this post, I will discuss the newly launched Ls-Series Azure virtual machines and how they are intended to be used.
The New Ls-Series Virtual Machines
Azure has a variety of ways to optimize the storage of virtual machines. Some, such as the D:, F-, G-, and H- series use drive capacity for the host to store the temp drive, which is then used for the temp drive. This is a virtual hard disk for the paging file and for disk-based caching. Any virtual machine with an S designation offers the ability to use Premium Storage. This is shared storage that is based on SSD disks.
Flash storage can offer low latency but Premium Storage is not local to the host. That means that there is always some additional latency between the host and the storage. The laws of physics cannot be bent to make packets move faster than the speed of electricity or light along the network cable.
The only way to reduce latency even further is to bring the storage closer to the host. And that is what the Ls-Series does. L is for Local or L is for Low Latency. Instead of using shared storage, Microsoft says that the LS-Series is “optimized for workloads that require low latency local storage.”
By using local storage, the virtual machine is running the same server as the data disks. Latency is as low as it can be while using current host architecture. The S in the Ls-Series tells us that the local storage is flash based. This means we have the benefits of:
- Low latency from flash storage
- Further reduced latency by using local storage
- Potentially very high IOPS
What sort of workloads would you consider for the Ls-Series? Microsoft designed these machines for services like NoSQL databases. A few examples of this are Cassandra, MongoDB, Cloudera, and Redis.
Specs and Performance
It appears that the Ls-Series virtual machines run on the same hosts as the G- and GS-Series virtual machines. They use the same Intel Xeon E5 v3 Haswell processors. Microsoft gives the machines the same Azure Compute Unit score of 180-240.
There are 4 virtual machines. They range from 4 cores, 32GiB RAM, up to 8 data disks, up to 32 cores, 256GiB RAM, and 64 data disks. Keep in mind, these are the real gigabytes that we learned about in computer science. They are not the x1000 ones designed by marketing people. Also note, the massive L32s machine is so big that the host will be dedicated to that customer!
Note that in the above table, all measurements are actually gibibyte (GiB). This is the computer science gigabyte of 1024MB.
The new method of naming virtual machines continues with the Ls-Series. The name indicates the number of cores, and once you know the series, you can tell how much RAM is included (x8 multiplier). You can also tell how many data disks it can support (x2 multiplier).
There is further evidence that the Ls-Series machines run on the same hardware as G-Series machines. You can only find Ls-Series availability in regions that already support the G-Series machines. Today, availability is limited to:
- Australia East
- Southeast Asia
- Japan East
- West Europe
- East US2
- West US
- US Gov Virginia
- Canada East
- Canada Central
Germany Central might be added later. It supports the G-Series. I do not expect any of the existing regions to add support soon. The high-cost G-Series has been around quite a while and has limited distribution throughout Azure.