{ "api_version": "1", "kind": "dse_post", "self": "https://update.dsesecurity.com/api/v1/posts/dse-20260917-033-check-reservation-flexibility-groups-before-matching-different-vm-sizes/", "item": { "id": "https://update.dsesecurity.com/updates/dse-20260917-033-check-reservation-flexibility-groups-before-matching-different-vm-sizes/", "slug": "dse-20260917-033-check-reservation-flexibility-groups-before-matching-different-vm-sizes", "url": "https://update.dsesecurity.com/updates/dse-20260917-033-check-reservation-flexibility-groups-before-matching-different-vm-sizes/", "alternate_urls": { "markdown": "https://update.dsesecurity.com/updates/dse-20260917-033-check-reservation-flexibility-groups-before-matching-different-vm-sizes.md", "json": "https://update.dsesecurity.com/api/v1/posts/dse-20260917-033-check-reservation-flexibility-groups-before-matching-different-vm-sizes/" }, "title": "Check reservation flexibility groups before matching different VM sizes", "summary": "DSE recommends recording each running VM’s exact size, its current flexibility group, and the applicable ratio before calculating coverage.", "format": { "slug": "guide", "name": "Guide" }, "priority": { "slug": "info", "name": "Information" }, "featured": false, "image": { "theme": "managed-it", "label": "Managed IT operations", "alt": "A controlled technology lifecycle progressing from assessment to approved production.", "card_url": "https://update.dsesecurity.com/assets/editorial/managed-it-card.webp?v=1.8.20", "hero_url": "https://update.dsesecurity.com/assets/editorial/managed-it-hero.webp?v=1.8.20", "social_url": "https://update.dsesecurity.com/assets/editorial/managed-it-social-v2.jpg?v=1.8.20", "width": 2400, "height": 1350 }, "topics": [ { "slug": "it", "name": "IT", "url": "https://update.dsesecurity.com/topic/it/" } ], "author": { "name": "DSE Security Editorial Team", "url": "https://update.dsesecurity.com/#editorial-team", "type": "Organization" }, "publisher": { "name": "Detection Systems & Engineering", "url": "https://dsesecurity.com/" }, "published_at": "2026-09-17T16:34:27+00:00", "modified_at": "2026-09-17T16:35:03+00:00", "reviewed_on": "2026-09-17", "reading_minutes": 1, "word_count": 212, "potentially_affected": "This is a technical matching check for teams reviewing reservation coverage across Azure VM sizes, with commercial decisions handled by their normal approval process.", "dse_recommendation": "DSE recommends recording each running VM’s exact size, its current flexibility group, and the applicable ratio before calculating coverage.", "primary_source": { "name": "Virtual machine size flexibility -Azure Reserved VM Instances - Azure Virtual Machines | Microsoft Learn", "url": "https://learn.microsoft.com/en-us/azure/virtual-machines/reserved-vm-instance-size-flexibility", "published_on": null, "authority": "Microsoft Learn" }, "publishing_principles": "https://update.dsesecurity.com/updates/dse-updates-editorial-methodology/", "usage_info": "https://update.dsesecurity.com/usage/", "copyright_notice": "Copyright © 2026 Detection Systems & Engineering. All rights reserved.", "content_html": "

Source facts

\n

Microsoft says an instance-size-flexible reservation applies across sizes inside the same flexibility group, not across different groups. The relative ratios of the purchased size and running sizes determine how much VM usage the reservation covers. The guide identifies API or PowerShell access as the replacement for the retired flexibility-ratio CSV. Microsoft Learn

\n

Applicability

\n

This is a technical matching check for teams reviewing reservation coverage across Azure VM sizes, with commercial decisions handled by their normal approval process.

\n

DSE recommendation

\n

DSE recommends recording each running VM’s exact size, its current flexibility group, and the applicable ratio before calculating coverage. Keep similarly named series separate until the group data confirms the relationship. Use the supported current data-access method and retain the retrieval date with the calculation. Have the resource owner reconcile the VM inventory before a financial reviewer considers purchase, exchange, or sizing decisions.

\n

Verification

\n

Recalculate the proposed matching using the recorded ratios and compare it with observed reservation application where available. Flag any VM outside the selected group and any missing or stale ratio data. Do not report a coverage estimate as realized savings; preserve the assumptions and unresolved differences with the review.

\n

Official references

\n", "content_text": "Source facts\nMicrosoft says an instance-size-flexible reservation applies across sizes inside the same flexibility group, not across different groups. The relative ratios of the purchased size and running sizes determine how much VM usage the reservation covers. The guide identifies API or PowerShell access as the replacement for the retired flexibility-ratio CSV. Microsoft Learn\nApplicability\nThis is a technical matching check for teams reviewing reservation coverage across Azure VM sizes, with commercial decisions handled by their normal approval process.\nDSE recommendation\nDSE recommends recording each running VM’s exact size, its current flexibility group, and the applicable ratio before calculating coverage. Keep similarly named series separate until the group data confirms the relationship. Use the supported current data-access method and retain the retrieval date with the calculation. Have the resource owner reconcile the VM inventory before a financial reviewer considers purchase, exchange, or sizing decisions.\nVerification\nRecalculate the proposed matching using the recorded ratios and compare it with observed reservation application where available. Flag any VM outside the selected group and any missing or stale ratio data. Do not report a coverage estimate as realized savings; preserve the assumptions and unresolved differences with the review.\nOfficial references\n\nMicrosoft: Virtual machine size flexibility -Azure Reserved VM Instances – Azure Virtual Machines | Microsoft Learn", "content_markdown": "## Source facts\n\nMicrosoft says an instance-size-flexible reservation applies across sizes inside the same flexibility group, not across different groups. The relative ratios of the purchased size and running sizes determine how much VM usage the reservation covers. The guide identifies API or PowerShell access as the replacement for the retired flexibility-ratio CSV. [Microsoft Learn](https://learn.microsoft.com/en-us/azure/virtual-machines/reserved-vm-instance-size-flexibility)\n\n## Applicability\n\nThis is a technical matching check for teams reviewing reservation coverage across Azure VM sizes, with commercial decisions handled by their normal approval process.\n\n## DSE recommendation\n\nDSE recommends recording each running VM’s exact size, its current flexibility group, and the applicable ratio before calculating coverage. Keep similarly named series separate until the group data confirms the relationship. Use the supported current data-access method and retain the retrieval date with the calculation. Have the resource owner reconcile the VM inventory before a financial reviewer considers purchase, exchange, or sizing decisions.\n\n## Verification\n\nRecalculate the proposed matching using the recorded ratios and compare it with observed reservation application where available. Flag any VM outside the selected group and any missing or stale ratio data. Do not report a coverage estimate as realized savings; preserve the assumptions and unresolved differences with the review.\n\n## Official references\n\n- [Microsoft: Virtual machine size flexibility -Azure Reserved VM Instances – Azure Virtual Machines | Microsoft Learn](https://learn.microsoft.com/en-us/azure/virtual-machines/reserved-vm-instance-size-flexibility)" }, "json_ld": { "@context": "https://schema.org", "@graph": [ { "@type": "Organization", "@id": "https://dsesecurity.com/#organization", "name": "Detection Systems & Engineering", "alternateName": "DSE Security", "url": "https://dsesecurity.com/", "logo": { "@type": "ImageObject", "url": "https://update.dsesecurity.com/assets/dse-logo-20260812.png?v=1.8.20" } }, { "@type": "Organization", "@id": "https://update.dsesecurity.com/#editorial-team", "name": "DSE Security Editorial Team", "url": "https://update.dsesecurity.com/", "parentOrganization": { "@id": "https://dsesecurity.com/#organization" } }, { "@type": "WebSite", "@id": "https://update.dsesecurity.com/#website", "name": "DSE Updates", "alternateName": "DSE Security Knowledge Hub", "url": "https://update.dsesecurity.com/", "inLanguage": "en-US", "publisher": { "@id": "https://dsesecurity.com/#organization" }, "potentialAction": { "@type": "SearchAction", "target": { "@type": "EntryPoint", "urlTemplate": "https://update.dsesecurity.com/?q={search_term_string}" }, "query-input": "required name=search_term_string" } }, { "@type": "WebPage", "@id": "https://update.dsesecurity.com/updates/dse-20260917-033-check-reservation-flexibility-groups-before-matching-different-vm-sizes/", "url": "https://update.dsesecurity.com/updates/dse-20260917-033-check-reservation-flexibility-groups-before-matching-different-vm-sizes/", "isPartOf": { "@id": "https://update.dsesecurity.com/#website" }, "lastReviewed": "2026-09-17" }, { "@type": "BreadcrumbList", "@id": "https://update.dsesecurity.com/updates/dse-20260917-033-check-reservation-flexibility-groups-before-matching-different-vm-sizes/#breadcrumbs", "itemListElement": [ { "@type": "ListItem", "position": 1, "name": "DSE Updates", "item": "https://update.dsesecurity.com/" }, { "@type": "ListItem", "position": 2, "name": "Check reservation flexibility groups before matching different VM sizes", "item": "https://update.dsesecurity.com/updates/dse-20260917-033-check-reservation-flexibility-groups-before-matching-different-vm-sizes/" } ] }, { "@type": [ "Article", "TechArticle" ], "@id": "https://update.dsesecurity.com/updates/dse-20260917-033-check-reservation-flexibility-groups-before-matching-different-vm-sizes/#article", "identifier": "https://update.dsesecurity.com/updates/dse-20260917-033-check-reservation-flexibility-groups-before-matching-different-vm-sizes/", "url": "https://update.dsesecurity.com/updates/dse-20260917-033-check-reservation-flexibility-groups-before-matching-different-vm-sizes/", "headline": "Check reservation flexibility groups before matching different VM sizes", "description": "DSE recommends recording each running VM’s exact size, its current flexibility group, and the applicable ratio before calculating coverage.", "abstract": "DSE recommends recording each running VM’s exact size, its current flexibility group, and the applicable ratio before calculating coverage.", "articleBody": "Source facts\nMicrosoft says an instance-size-flexible reservation applies across sizes inside the same flexibility group, not across different groups. The relative ratios of the purchased size and running sizes determine how much VM usage the reservation covers. The guide identifies API or PowerShell access as the replacement for the retired flexibility-ratio CSV. Microsoft Learn\nApplicability\nThis is a technical matching check for teams reviewing reservation coverage across Azure VM sizes, with commercial decisions handled by their normal approval process.\nDSE recommendation\nDSE recommends recording each running VM’s exact size, its current flexibility group, and the applicable ratio before calculating coverage. Keep similarly named series separate until the group data confirms the relationship. Use the supported current data-access method and retain the retrieval date with the calculation. Have the resource owner reconcile the VM inventory before a financial reviewer considers purchase, exchange, or sizing decisions.\nVerification\nRecalculate the proposed matching using the recorded ratios and compare it with observed reservation application where available. Flag any VM outside the selected group and any missing or stale ratio data. Do not report a coverage estimate as realized savings; preserve the assumptions and unresolved differences with the review.\nOfficial references\n\nMicrosoft: Virtual machine size flexibility -Azure Reserved VM Instances – Azure Virtual Machines | Microsoft Learn", "datePublished": "2026-09-17T16:34:27+00:00", "dateModified": "2026-09-17T16:35:03+00:00", "mainEntityOfPage": { "@id": "https://update.dsesecurity.com/updates/dse-20260917-033-check-reservation-flexibility-groups-before-matching-different-vm-sizes/" }, "inLanguage": "en-US", "isAccessibleForFree": true, "author": { "@type": "Organization", "name": "DSE Security Editorial Team", "url": "https://update.dsesecurity.com/#editorial-team" }, "publisher": { "@id": "https://dsesecurity.com/#organization" }, "image": { "@type": "ImageObject", "@id": "https://update.dsesecurity.com/updates/dse-20260917-033-check-reservation-flexibility-groups-before-matching-different-vm-sizes/#primaryimage", "url": "https://update.dsesecurity.com/assets/editorial/managed-it-social-v2.jpg?v=1.8.20", "contentUrl": "https://update.dsesecurity.com/assets/editorial/managed-it-social-v2.jpg?v=1.8.20", "width": 1200, "height": 630, "caption": "Check reservation flexibility groups before matching different VM sizes" }, "articleSection": [ "IT" ], "keywords": [ "IT", "Guide", "Information priority" ], "genre": "Guide", "about": [ { "@type": "Thing", "name": "IT", "url": "https://update.dsesecurity.com/topic/it/" } ], "wordCount": 212, "timeRequired": "PT1M", "publishingPrinciples": "https://update.dsesecurity.com/updates/dse-updates-editorial-methodology/", "usageInfo": "https://update.dsesecurity.com/usage/", "copyrightHolder": { "@id": "https://dsesecurity.com/#organization" }, "copyrightNotice": "Copyright © 2026 Detection Systems & Engineering. All rights reserved.", "citation": { "@type": "CreativeWork", "name": "Virtual machine size flexibility -Azure Reserved VM Instances - Azure Virtual Machines | Microsoft Learn", "url": "https://learn.microsoft.com/en-us/azure/virtual-machines/reserved-vm-instance-size-flexibility" } } ] } }