Update best practices for Linux on Hyper-V

Added important notes on using Hyper-V-specific network adapters. When more than 2 vCPUs are assigned to a Linux guest, the VM may not see the maximum of 64 virtual Ethernet adapters.

Author: jaysenb

WindowsServerDocs/virtualization/hyper-v/Best-Practices-for-running-Linux-on-Hyper-V.md

@@ -61,6 +61,9 @@ Linux virtual machines deployed using failover clustering should be configured w
 
 Configure and use the virtual Ethernet adapter, which is a Hyper-V-specific network card with enhanced performance. If both legacy and Hyper-V-specific network adapters are attached to a virtual machine, the network names in the output of **ifconfig -a** might show random values such as **_tmp12000801310**. To avoid this issue, remove all legacy network adapters when using Hyper-V-specific network adapters in a Linux virtual machine.
 
+> [!IMPORTANT]
+> Hyper-V supports up to 64 virtual Ethernet adapters per guest. In some Linux guest configurations, the maximum number of virtual Ethernet adapters may be less than 64. For more information about Hyper-V scale limits see: [Hyper-V maximum scale limits in Windows Server](https://learn.microsoft.com/en-us/windows-server/virtualization/hyper-v/maximum-scale-limits?tabs=windows-server-2025)
+
 ## Use I/O scheduler noop/none for better disk I/O performance
 
 The Linux kernel offers two sets of disk I/O schedulers to reorder requests.  One set is for the older 'blk' subsystem and one set is for the newer 'blk-mq' subsystem. In either case, with today’s solid state disks it's recommended to use a scheduler that passes the scheduling decisions to the underlying Hyper-V hypervisor. For Linux kernels using the 'blk' subsystem, this is the "noop" scheduler. For Linux kernels using the 'blk-mq' subsystem, this is the "none" scheduler.