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Bug #395

closed

OAM: VM disk cache optimization (writethrough -> writeback) + tuned deployment

Bug #395: OAM: VM disk cache optimization (writethrough -> writeback) + tuned deployment

Added by Charles N 1 day ago. Updated about 17 hours ago.

Status:
Resolved
Priority:
Normal
Assignee:
Charles N
Target version:
-
Start date:
08/06/2026
Due date:
% Done:

100%

Estimated time:

Description

Two-part infrastructure optimization across all Proxmox hosts and VMs.

Part 1: VM disk cache changes

VMs still using cache=writethrough on NFS-backed spinning disk should be changed to cache=writeback for consistency and performance. Writethrough forces every guest fsync to physical spinning disk (slow). Writeback lets host RAM absorb fsyncs (fast, safe for this R&D cluster).

VMs to change (requires stop/set/start):

  • VMID 108 tsys-ucs-01 (tsys1) — writethrough -> writeback
  • VMID 600 tsys-awx (tsys6) — writethrough -> writeback
  • VMID 703 rr-middleware-01 (tsys7) — writethrough -> writeback
  • VMID 706 kali-rd (tsys7) — writethrough -> writeback
  • VMID 707 tsys-siem (tsys7) — writethrough -> writeback

DO NOT REBOOT: ultix-streaming, ultix-offstage, pfv-netinfra-01, pfv-netinfra-02

VMs with no cache setting (default=none): evaluate and set writeback where appropriate.
VMs on local-lvm: leave as-is (local disk doesn't need writeback).

Part 2: tuned deployment

Hypervisors (Proxmox hosts):

  • Profile: virtual-host (optimizes CPU scheduling, I/O for virtualization)
  • Install tuned + tuned-utils, set profile, enable service

VMs (guests):

  • Profile: network-latency for k8s/storage-sensitive VMs
  • Profile: throughput-performance for general workloads
  • Install tuned, set appropriate profile per VM

Related: #391 (original writeback change on cnodes), #393 (network audit)

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