Utilize Managed Disk for Service Fabric temporary storage

Question

Is it possible to configure and deploy a Service Fabric cluster that uses a Managed Disk as the temporary storage location for things like the replicator log and app type/versions?

For example, I can't use an A1_v2 VM instance size because the D: (Temporary Storage) drive is too small. If I could leverage a Managed Disk and configure SF to use it instead of the local SSD then this instance size would work for my dev/test scenarios.

Any idea if and how I can make this work?

masnider masnider · Accepted Answer · 2017-02-28T23:48:52

Disclaimer: You can do this, but you shouldn't. Details below.

Consider changing the size of the shared log file instead if you really want to use such small VMs.

"fabricSettings": [{
    "name": "KtlLogger",
    "parameters": [{
        "name": "SharedLogSizeInMB",
        "value": "4096"
    }]
}]

More info on configuration here.

Now to actually answer:

Here are the settings. You'd probably change Setup/FabricDataRoot to move the Service Fabric local installation and all of the local application working directories, and/or TransactionalReplicator/SharedLogPath to move the reliable collections shared log.

Some things to consider:

Service Fabric Services (and Service Fabric itself) are built to work on local disks and generally should not be hosted on XStore backed disks (premium or not):

Reliable Collections are definitely built to operate against local drives. There's no internal testing that I'm aware of that runs them in this configuration.
Waste of IO: Assuming LRS replicates changes 3 times and you set TargetReplicaSetSize to 3, this configuration will generate 9 copies of the state. Do you need 9 copies of your state?
Impact on Latency and Performance: What should be a local disk IO will turn into network + disk IO, which has a chance to hurt your performance.
Impact on Availability: At a minimum you're adding another dependency, which usually reduces overall availability. If storage ever has an issue you're now more coupled to that other service. Today you're pretty coupled already since the VMSS drives are backed by blobs, so VM provisioning would fail, but that's different than the read/write/activation path for your services.

Utilize Managed Disk for Service Fabric temporary storage

1 Answers