{"id":362,"date":"2025-04-07T16:52:22","date_gmt":"2025-04-07T16:52:22","guid":{"rendered":"http:\/\/remote-support.space\/wordpress\/?p=362"},"modified":"2025-04-07T16:52:22","modified_gmt":"2025-04-07T16:52:22","slug":"proxmox-vm-disk-size-limits-explained","status":"publish","type":"post","link":"http:\/\/remote-support.space\/wordpress\/2025\/04\/07\/proxmox-vm-disk-size-limits-explained\/","title":{"rendered":"Proxmox VM Disk Size Limits Explained"},"content":{"rendered":"\n<p>The maximum disk size you can assign to a VM in Proxmox depends on several factors, including the underlying storage technology, filesystem, and VM configuration. Here\u2019s a summary of the key limitations:<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">1. <strong>Storage Technology Limitations<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>LVM (Logical Volume Manager)<\/strong>:\n<ul class=\"wp-block-list\">\n<li>For 64-bit systems with Linux 2.6+ kernels, the maximum LV size is <strong>8 Exabytes (EB)<\/strong>1.<\/li>\n\n\n\n<li>For older 32-bit systems or 2.4 kernels, the limit is <strong>2TB<\/strong>1.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>ZFS<\/strong>:\n<ul class=\"wp-block-list\">\n<li>Theoretical maximum is <strong>16 Exabytes (EB)<\/strong>, though hardware constraints may apply27.<\/li>\n\n\n\n<li>For file-based <code>.raw<\/code> volumes on <strong>ext4<\/strong>, the limit is <strong>16 TiB<\/strong> (with 4K blocks)2.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Ceph RBD<\/strong>: No inherent limits from RBD\/QEMU, but practical constraints (e.g., VM disk controller type like VirtIO-SCSI) may apply. Even <strong>2PB disks<\/strong> are theoretically possible2.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">2. <strong>Filesystem Overhead<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>ZFS RAIDZ<\/strong> configurations (e.g., RAIDZ1\/2) incur overhead due to parity and padding. For example:\n<ul class=\"wp-block-list\">\n<li>A 3x 3TB RAIDZ1 pool with default settings may lose ~50% of raw capacity to parity and padding, leaving ~3.6TB usable4.<\/li>\n\n\n\n<li>Increasing <code>volblocksize<\/code> (e.g., to 16K) can reduce padding overhead4.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">3. <strong>VM Configuration<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>VirtIO-SCSI<\/strong> supports near-unlimited disks, but some users report limits around <strong>30 devices<\/strong> per VM5. For larger setups, PCI passthrough of HBAs is recommended5.<\/li>\n\n\n\n<li><strong>Disk Controllers<\/strong>: IDE has lower limits compared to VirtIO or SCSI. For large disks, use <strong>VirtIO-SCSI<\/strong> or <strong>VirtIO-block<\/strong>26.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">4. <strong>Practical Considerations<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Proxmox GUI Defaults<\/strong>: The web interface may default to TiB\/GiB (binary units), which can cause confusion (e.g., 32GiB \u2260 32GB)9.<\/li>\n\n\n\n<li><strong>Thin Provisioning<\/strong>: LVM-thin or ZFS allows overallocation, but physical storage must eventually match usage89.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">5. <strong>Hardware Constraints<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>HBA\/RAID Cards<\/strong>: Some adapters (e.g., Adaptec) may impose partition limits (e.g., 2TB for boot volumes)1.<\/li>\n\n\n\n<li><strong>Network Storage<\/strong>: Performance may bottleneck on network speed (e.g., OVH\u2019s internal network limiting striped ZFS speeds)5.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Recommendations:<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>For <strong>>2TB disks<\/strong>, use <strong>64-bit Proxmox, ZFS\/VirtIO-SCSI, and modern kernels<\/strong>.<\/li>\n\n\n\n<li>For <strong>multi-petabyte disks<\/strong>, verify controller\/filesystem support (e.g., ZFS or Ceph RBD)27.<\/li>\n\n\n\n<li>Monitor <strong>RAM requirements<\/strong> for ZFS (rule of thumb: 1GB RAM per 1TB storage for performance)5.<\/li>\n<\/ul>\n\n\n\n<p>For specific setups, consult the <a href=\"https:\/\/pve.proxmox.com\/wiki\/Storage\" target=\"_blank\" rel=\"noreferrer noopener\">Proxmox documentation<\/a> or community forums.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>The maximum disk size you can assign to a VM in Proxmox depends on several factors, including the underlying storage technology, filesystem, and VM configuration. Here\u2019s a summary of the key limitations: 1. Storage Technology Limitations 2. Filesystem Overhead 3. VM Configuration 4. Practical Considerations 5. Hardware Constraints Recommendations: For specific setups, consult the Proxmox [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-362","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"http:\/\/remote-support.space\/wordpress\/wp-json\/wp\/v2\/posts\/362","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/remote-support.space\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/remote-support.space\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/remote-support.space\/wordpress\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/remote-support.space\/wordpress\/wp-json\/wp\/v2\/comments?post=362"}],"version-history":[{"count":1,"href":"http:\/\/remote-support.space\/wordpress\/wp-json\/wp\/v2\/posts\/362\/revisions"}],"predecessor-version":[{"id":363,"href":"http:\/\/remote-support.space\/wordpress\/wp-json\/wp\/v2\/posts\/362\/revisions\/363"}],"wp:attachment":[{"href":"http:\/\/remote-support.space\/wordpress\/wp-json\/wp\/v2\/media?parent=362"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/remote-support.space\/wordpress\/wp-json\/wp\/v2\/categories?post=362"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/remote-support.space\/wordpress\/wp-json\/wp\/v2\/tags?post=362"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}