{"id":776,"date":"2026-07-01T10:09:42","date_gmt":"2026-07-01T10:09:42","guid":{"rendered":"https:\/\/www.lighthouse-program.com\/?p=776"},"modified":"2026-07-01T10:09:42","modified_gmt":"2026-07-01T10:09:42","slug":"lessi-learned-week-27-2026","status":"publish","type":"post","link":"https:\/\/www.lighthouse-program.com\/?p=776","title":{"rendered":"Lessi learned \u2013 week 27\/2026"},"content":{"rendered":"\n<p class=\"has-vivid-cyan-blue-color has-text-color has-link-color wp-elements-a8ceba65b82e08fd63d02ebcf0f9b2ff wp-block-paragraph\"><strong>Welcome to the \u201cLessi Learned\u201d Newsletter!<\/strong><\/p>\n\n\n\n<div style=\"height:28px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"alignright size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"307\" height=\"205\" src=\"https:\/\/www.lighthouse-program.com\/wp-content\/uploads\/2026\/07\/v131-summer.png\" alt=\"\" class=\"wp-image-779\" srcset=\"https:\/\/www.lighthouse-program.com\/wp-content\/uploads\/2026\/07\/v131-summer.png 307w, https:\/\/www.lighthouse-program.com\/wp-content\/uploads\/2026\/07\/v131-summer-300x200.png 300w, https:\/\/www.lighthouse-program.com\/wp-content\/uploads\/2026\/07\/v131-summer-210x140.png 210w\" sizes=\"auto, (max-width: 307px) 100vw, 307px\" \/><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">Even as summer approaches and a slightly quieter period may be ahead due to holiday season, there is still a lot happening at Veeam. Version 13.1 is just around the corner and will introduce a wide range of new features and enhancements.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">For anyone considering the VSA, please make sure to review the information from my previous newsletter to avoid any limitations that could impact a potential migration.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">At the same time, all other products continue to receive regular updates and improvements. so enjoy this edition and happy reading.<\/p>\n\n\n\n<div style=\"height:19px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-8f761849 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:50%\">\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-8f761849 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:100%\">\n<div class=\"wp-block-group is-nowrap is-layout-flex wp-container-core-group-is-layout-8f761849 wp-block-group-is-layout-flex\">\n<div class=\"wp-block-media-text is-stacked-on-mobile\" style=\"grid-template-columns:17% auto\"><figure class=\"wp-block-media-text__media\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"1024\" src=\"https:\/\/www.lighthouse-program.com\/wp-content\/uploads\/2025\/10\/lightning.png\" alt=\"\" class=\"wp-image-297 size-full\" srcset=\"https:\/\/www.lighthouse-program.com\/wp-content\/uploads\/2025\/10\/lightning.png 1024w, https:\/\/www.lighthouse-program.com\/wp-content\/uploads\/2025\/10\/lightning-300x300.png 300w, https:\/\/www.lighthouse-program.com\/wp-content\/uploads\/2025\/10\/lightning-150x150.png 150w, https:\/\/www.lighthouse-program.com\/wp-content\/uploads\/2025\/10\/lightning-768x768.png 768w, https:\/\/www.lighthouse-program.com\/wp-content\/uploads\/2025\/10\/lightning-210x210.png 210w\" sizes=\"auto, (max-width: 980px) 100vw, 980px\" \/><\/figure><div class=\"wp-block-media-text__content\">\n<h1 class=\"wp-block-heading\"><strong>Newsflash<\/strong><\/h1>\n<\/div><\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n<p class=\"has-vivid-cyan-blue-color has-text-color has-link-color wp-elements-8e62148cce26f2512bdaba12af8c8190 wp-block-paragraph\"><strong>Veeam Backup for M365 Version 8.5<\/strong><\/p>\n\n\n\n<div style=\"height:19px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<p class=\"wp-block-paragraph\">The new version is now available, and it is strongly recommended to plan the upgrade as part of your regular maintenance cycle to ensure continued supportability and optimal system performance.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Key highlights include:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Improved compatibility with recent platform updates and supported infrastructure components<\/li>\n\n\n\n<li>Resolved issues affecting backup job processing and application consistency in specific scenarios<\/li>\n\n\n\n<li>General performance and stability enhancements across core backup and replication workflows<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Link to: <a href=\"https:\/\/www.veeam.com\/kb4873?utm_source=lighthouse-program.com\" data-type=\"link\" data-id=\"https:\/\/www.veeam.com\/kb4873?utm_source=lighthouse-program.com\" target=\"_blank\" rel=\"noreferrer noopener\">Release Notes<\/a><\/p>\n\n\n\n<div style=\"height:31px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:31px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<p class=\"has-vivid-cyan-blue-color has-text-color has-link-color wp-elements-064136bf895cdaa6f0af4ab3647b1281 wp-block-paragraph\"><strong>Fix for Veeam Backup for M365 Data Integrity Issue<\/strong><\/p>\n\n\n\n<div style=\"height:18px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<p class=\"wp-block-paragraph\">The issue described in <a href=\"https:\/\/www.veeam.com\/kb4874?utm_source=lighthouse-program.com\" data-type=\"link\" data-id=\"https:\/\/www.veeam.com\/kb4874?utm_source=\" target=\"_blank\" rel=\"noreferrer noopener\">KB4874<\/a> is connected to the data integrity problem first outlined in <strong><a href=\"https:\/\/www.veeam.com\/kb4835?utm_source=lighthouse-program.com\" data-type=\"link\" data-id=\"https:\/\/www.veeam.com\/kb4835?utm_source=lighthouse-program.com\" target=\"_blank\" rel=\"noreferrer noopener\">KB4835<\/a><\/strong>, which was initially observed in early March 2026. In some cases, files backed up from Microsoft 365 workloads (such as SharePoint, OneDrive, and Teams) could contain error page content instead of the actual data, which may result in unusable items during restore.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A fix is now available for environments using S3 or S3-compatible object storage without immutability enabled. In these cases, the KB provides clear steps to identify and correct affected data.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">For JetDB-based repositories, the situation is different. A final fix is still in progress, and investigations are ongoing.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The remediation requires Veeam Backup for Microsoft 365 version 8.5. After upgrading, the steps in KB4874 should be followed to resolve the issue where applicable.<\/p>\n\n\n\n<p class=\"has-luminous-vivid-amber-color has-text-color has-link-color wp-elements-e093a4c3d8d567359b69040dadaf3956 wp-block-paragraph\"><strong>Related KB articles:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><a href=\"https:\/\/www.veeam.com\/kb4874?utm_source=lighthouse-program.com\" data-type=\"link\" data-id=\"https:\/\/www.veeam.com\/kb4874?utm_source=lighthouse-program.com\" target=\"_blank\" rel=\"noreferrer noopener\">KB4874 \u2013 Repository-specific remediation steps<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/www.veeam.com\/kb4835?utm_source=lighthouse-program.com\" data-type=\"link\" data-id=\"https:\/\/www.veeam.com\/kb4835?utm_source=lighthouse-program.com\" target=\"_blank\" rel=\"noreferrer noopener\">KB4835 \u2013 Root cause and background of the data integrity issue<\/a><\/li>\n<\/ul>\n\n\n\n<div style=\"height:25px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:39px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-8f761849 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:50%\">\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-8f761849 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:100%\">\n<div class=\"wp-block-group is-nowrap is-layout-flex wp-container-core-group-is-layout-8f761849 wp-block-group-is-layout-flex\">\n<div class=\"wp-block-media-text is-stacked-on-mobile\" style=\"grid-template-columns:17% auto\"><figure class=\"wp-block-media-text__media\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"1024\" src=\"https:\/\/www.lighthouse-program.com\/wp-content\/uploads\/2025\/10\/bulb.png\" alt=\"\" class=\"wp-image-300 size-full\" srcset=\"https:\/\/www.lighthouse-program.com\/wp-content\/uploads\/2025\/10\/bulb.png 1024w, https:\/\/www.lighthouse-program.com\/wp-content\/uploads\/2025\/10\/bulb-300x300.png 300w, https:\/\/www.lighthouse-program.com\/wp-content\/uploads\/2025\/10\/bulb-150x150.png 150w, https:\/\/www.lighthouse-program.com\/wp-content\/uploads\/2025\/10\/bulb-768x768.png 768w, https:\/\/www.lighthouse-program.com\/wp-content\/uploads\/2025\/10\/bulb-210x210.png 210w\" sizes=\"auto, (max-width: 980px) 100vw, 980px\" \/><\/figure><div class=\"wp-block-media-text__content\">\n<h1 class=\"wp-block-heading\"><strong>Lessons learned<\/strong><\/h1>\n<\/div><\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<p class=\"has-vivid-cyan-blue-color has-text-color has-link-color wp-elements-9d145aecc8a3b0c03c54e2b74074a6e5 wp-block-paragraph\"><strong>Wrong assumptions: Block Generation and Repository Sizing<\/strong><\/p>\n\n\n\n<div style=\"height:24px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"alignright size-full is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"251\" height=\"251\" src=\"https:\/\/www.lighthouse-program.com\/wp-content\/uploads\/2026\/07\/block-generation.png\" alt=\"\" class=\"wp-image-781\" style=\"width:288px;height:auto\" srcset=\"https:\/\/www.lighthouse-program.com\/wp-content\/uploads\/2026\/07\/block-generation.png 251w, https:\/\/www.lighthouse-program.com\/wp-content\/uploads\/2026\/07\/block-generation-150x150.png 150w, https:\/\/www.lighthouse-program.com\/wp-content\/uploads\/2026\/07\/block-generation-210x210.png 210w\" sizes=\"auto, (max-width: 251px) 100vw, 251px\" \/><\/figure>\n<\/div>\n\n\n<p class=\"wp-block-paragraph\">It has been observed that \u201cblock generation\u201d sometimes creates confusion when sizing repositories, as it is sometimes incorrectly assumed to apply to XFS or ReFS-based repositories. In reality, block generation <strong>is only relevant for Object Storage repositories<\/strong>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The purpose of block generation is to reduce API overhead by caching and reusing object-level block metadata, thereby avoiding repeated LIST and HEAD operations against the storage backend during incremental processing. This improves efficiency and performance, especially in large-scale environments.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">In Veeam-based object storage integrations (e.g., S3-compatible targets), the default block generation retention is typically around 10 days. In AWS environments, effective retention may be longer depending on bucket lifecycle and storage policies (often 30+ days or more), which further influences how long metadata and object state remain relevant for optimization.<\/p>\n\n\n\n<div style=\"height:39px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:39px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h3 class=\"wp-block-heading\">Thanks for reading<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">I hope you enjoyed this edition of my Lessi-Learned Newsletter. Thank you for reading!<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Got feedback or something you want to see in the next edition? Leave a comment, write me on X (<a href=\"https:\/\/x.com\/lessi001\" data-type=\"link\" data-id=\"https:\/\/x.com\/lessi001\" target=\"_blank\" rel=\"noreferrer noopener\">@lessi001<\/a>) or connect at <a href=\"https:\/\/www.linkedin.com\/in\/andreas-lesslhumer-2bb2725b\/\" target=\"_blank\" rel=\"noreferrer noopener\">LinkedIn<\/a>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Want to get the newsletter hot off the press? Sign up for my mailing list and I\u2019ll drop a note in your inbox as soon as the latest issue is ready:<\/p>\n\n\n\n<div class=\"wp-block-noptin-email-optin is-style-noptin-flex has-black-background-color has-background has-small-font-size\"><form><div class=\"noptin-block-form-header\">\n<h2 class=\"wp-block-heading noptin_form_title\">Subscribe to the Newsletter:<\/h2>\n<\/div><div class=\"noptin-block-form-footer\"><input type=\"email\" class=\"noptin_form_input_email\" placeholder=\"Email Address\" name=\"noptin_fields[email]\" required\/><input value=\"SUBSCRIBE\" type=\"submit\" class=\"noptin_form_submit wp-element-button\"\/><\/div><div class=\"noptin-form-notice noptin-response\" role=\"alert\"><\/div><input type=\"hidden\" name=\"source\" value=\"block\"\/><\/form><\/div>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Welcome to the \u201cLessi Learned\u201d Newsletter! Even as summer approaches and a slightly quieter period may be ahead due to holiday season, there is still a lot happening at Veeam. Version 13.1 is just around the corner and will introduce a wide range of new features and enhancements. For anyone considering the VSA, please make [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6],"tags":[],"class_list":["post-776","post","type-post","status-publish","format-standard","hentry","category-newsletter"],"_links":{"self":[{"href":"https:\/\/www.lighthouse-program.com\/index.php?rest_route=\/wp\/v2\/posts\/776","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.lighthouse-program.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.lighthouse-program.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.lighthouse-program.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.lighthouse-program.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=776"}],"version-history":[{"count":5,"href":"https:\/\/www.lighthouse-program.com\/index.php?rest_route=\/wp\/v2\/posts\/776\/revisions"}],"predecessor-version":[{"id":783,"href":"https:\/\/www.lighthouse-program.com\/index.php?rest_route=\/wp\/v2\/posts\/776\/revisions\/783"}],"wp:attachment":[{"href":"https:\/\/www.lighthouse-program.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=776"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.lighthouse-program.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=776"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.lighthouse-program.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=776"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}