Azure Discovery will ignore temporary disks, setting apprently incorrect Linux Disk spaceIssue <!-- /*NS Branding Styles*/ --> .ns-kb-css-body-editor-container { p { font-size: 12pt; font-family: Lato; color: var(--now-color--text-primary, #000000); } span { font-size: 12pt; font-family: Lato; color: var(--now-color--text-primary, #000000); } h2 { font-size: 24pt; font-family: Lato; color: var(--now-color--text-primary, black); } h3 { font-size: 18pt; font-family: Lato; color: var(--now-color--text-primary, black); } h4 { font-size: 14pt; font-family: Lato; color: var(--now-color--text-primary, black); } a { font-size: 12pt; font-family: Lato; color: var(--now-color--link-primary, #00718F); } a:hover { font-size: 12pt; color: var(--now-color--link-primary, #024F69); } a:target { font-size: 12pt; color: var(--now-color--link-primary, #032D42); } a:visited { font-size: 12pt; color: var(--now-color--link-primary, #00718f); } ul { font-size: 12pt; font-family: Lato; } li { font-size: 12pt; font-family: Lato; } img { display: ; max-width: ; width: ; height: ; } } Discovery does not appear to correctly populate the Disk space (GB) attribute (disk_space) on the cmdb_ci_linux_server table, on hosts where an Azure temporary disk (e.g. sdb) is present. According to ServiceNow documentation, the disk_space field represents: "An aggregation of the total capacity (including used space) for all non‑removable disks, including both directly attached and SAN storage." Reference:Linux discovery Symptoms<!-- /*NS Branding Styles*/ --> .ns-kb-css-body-editor-container { p { font-size: 12pt; font-family: Lato; color: var(--now-color--text-primary, #000000); } span { font-size: 12pt; font-family: Lato; color: var(--now-color--text-primary, #000000); } h2 { font-size: 24pt; font-family: Lato; color: var(--now-color--text-primary, black); } h3 { font-size: 18pt; font-family: Lato; color: var(--now-color--text-primary, black); } h4 { font-size: 14pt; font-family: Lato; color: var(--now-color--text-primary, black); } a { font-size: 12pt; font-family: Lato; color: var(--now-color--link-primary, #00718F); } a:hover { font-size: 12pt; color: var(--now-color--link-primary, #024F69); } a:target { font-size: 12pt; color: var(--now-color--link-primary, #032D42); } a:visited { font-size: 12pt; color: var(--now-color--link-primary, #00718f); } ul { font-size: 12pt; font-family: Lato; } li { font-size: 12pt; font-family: Lato; } img { display: ; max-width: ; width: ; height: ; } } Review Horizontal Discovery Execution Pattern Step: 18.2.14 – Set server object_id Confirm that the Linux Server CI receives an object_id, as shown in the sample pattern log below: 2026-03-09 11:20:44: setAttribute(cmdb_ci_linux_server[*].object_id, 2026-03-09 11:20:44: setAttribute(cmdb_ci_linux_server,[{ cpu_speed=2294, cpu_core_thread=2, model_id=Virtual Machine, disk_space=1472.00, ram=257418.0 }]) Execution time: 1 ms At this stage, the initial disk_space is correctly calculated as 1472 GB. 3. Azure Post‑Processing Step – Disk Space Adjustment Pattern Step: 18.2.15 – Update total disk space by removing temporary Azure disk 2026-03-09 11:20:44: setAttribute(cmdb_ci_linux_server[*].disk_space,1344.0) 2026-03-09 11:20:44: setAttribute(cmdb_ci_linux_server,[{ ... disk_space=1344.0, }]) Execution time: 1 ms Result disk_space changes from 1472 GB → 1344 GBThe difference (~128 GB) corresponds to the Azure temporary disk. 4. Script Used for Temporary Disk Removal The following script is executed to identify and subtract Azure temporary disks: var getTotalDiskSpaceByTableForTempDisk = function(disksTable) { var totalDiskSpace = 0; if (disksTable != null) { var currentDisk; for (var i = 0; i < disksTable.size(); i++) { current = disksTable.get(i); var current_disk_name = String(currentDisk.get("device_id")); var current_disk_space = currentDisk.get("disk_space"); if (current_disk_space && current_disk_name.includes("sdb")) { totalDiskSpace = parseFloat(totalDiskSpace) + parseFloat(current_disk_space); } } } return totalDiskSpace; }; diskUsage = parseFloat(getTotalDiskSpaceByTableForTempDisk(disks)); rtrn = parseFloat(curSpace) - parseFloat(diskUsage); Key point The disk name sdb is hardcoded and represents the Azure temporary disk. 5. Disk Space Calculation Flow Initial disk aggregation Disk capacity is aggregated from: cmdb_ci_diskcmdb_ci_storage_device This produces the correct total disk_space = 1472 GB. Azure‑specific post‑processing Pattern step: "Update total disk space by removing temporary azure disk"This step modifies disk_space after it has already been set. Release<!-- /*NS Branding Styles*/ --> .ns-kb-css-body-editor-container { p { font-size: 12pt; font-family: Lato; color: var(--now-color--text-primary, #000000); } span { font-size: 12pt; font-family: Lato; color: var(--now-color--text-primary, #000000); } h2 { font-size: 24pt; font-family: Lato; color: var(--now-color--text-primary, black); } h3 { font-size: 18pt; font-family: Lato; color: var(--now-color--text-primary, black); } h4 { font-size: 14pt; font-family: Lato; color: var(--now-color--text-primary, black); } a { font-size: 12pt; font-family: Lato; color: var(--now-color--link-primary, #00718F); } a:hover { font-size: 12pt; color: var(--now-color--link-primary, #024F69); } a:target { font-size: 12pt; color: var(--now-color--link-primary, #032D42); } a:visited { font-size: 12pt; color: var(--now-color--link-primary, #00718f); } ul { font-size: 12pt; font-family: Lato; } li { font-size: 12pt; font-family: Lato; } img { display: ; max-width: ; width: ; height: ; } } All release Cause<!-- /*NS Branding Styles*/ --> .ns-kb-css-body-editor-container { p { font-size: 12pt; font-family: Lato; color: var(--now-color--text-primary, #000000); } span { font-size: 12pt; font-family: Lato; color: var(--now-color--text-primary, #000000); } h2 { font-size: 24pt; font-family: Lato; color: var(--now-color--text-primary, black); } h3 { font-size: 18pt; font-family: Lato; color: var(--now-color--text-primary, black); } h4 { font-size: 14pt; font-family: Lato; color: var(--now-color--text-primary, black); } a { font-size: 12pt; font-family: Lato; color: var(--now-color--link-primary, #00718F); } a:hover { font-size: 12pt; color: var(--now-color--link-primary, #024F69); } a:target { font-size: 12pt; color: var(--now-color--link-primary, #032D42); } a:visited { font-size: 12pt; color: var(--now-color--link-primary, #00718f); } ul { font-size: 12pt; font-family: Lato; } li { font-size: 12pt; font-family: Lato; } img { display: ; max-width: ; width: ; height: ; } } From Linux Server pattern execution, the CI is identified as Azure: manufacturer = Microsoft Corporationmodel_id = Virtual MachineAzure metadata detected → isAzure = true Because the CI is identified as Azure: The pattern executes "Update total disk space by removing temporary azure disk"The script searches for disks like sdbThe disk size is subtracted from the previously calculated total Final Outcome Initial disk_space: 1472 GBAzure temporary disk (sdb): ~128 GBFinal disk_space: 1344 GB Resolution<!-- /*NS Branding Styles*/ --> .ns-kb-css-body-editor-container { p { font-size: 12pt; font-family: Lato; color: var(--now-color--text-primary, #000000); } span { font-size: 12pt; font-family: Lato; color: var(--now-color--text-primary, #000000); } h2 { font-size: 24pt; font-family: Lato; color: var(--now-color--text-primary, black); } h3 { font-size: 18pt; font-family: Lato; color: var(--now-color--text-primary, black); } h4 { font-size: 14pt; font-family: Lato; color: var(--now-color--text-primary, black); } a { font-size: 12pt; font-family: Lato; color: var(--now-color--link-primary, #00718F); } a:hover { font-size: 12pt; color: var(--now-color--link-primary, #024F69); } a:target { font-size: 12pt; color: var(--now-color--link-primary, #032D42); } a:visited { font-size: 12pt; color: var(--now-color--link-primary, #00718f); } ul { font-size: 12pt; font-family: Lato; } li { font-size: 12pt; font-family: Lato; } img { display: ; max-width: ; width: ; height: ; } } This behavior is by design, confirmed by developers in April 2026. On Microsoft Azure, the temporary disk provided with a Linux virtual machine is not intended to be included in the total persistent disk capacity. As a result, ServiceNow Discovery explicitly excludes this disk when calculating disk_space for Azure Linux servers. Microsoft documents this behavior clearly: the temporary disk is ephemeral, non‑persistent, and should not be considered part of the VM's usable storage capacity. ReferenceMicrosoft Learn – Format and mount a temporary disk on a Linux VMMicrosoft Learn: Format and mount temporary disk to Azure Linux VMsLink: Microsoft Learn: Tutorial - Manage Azure disks with the Azure CLI"Temporary disks are labeled /dev/sdb" Conclusion The reduction in disk_space is expected and intentionalAzure temporary disks (for example, sdb) are excluded from total disk calculationsNo corrective action is required, as the discovery result reflects the supported and documented Azure design