{"id":"external-drives.what-is-the-efi-partition","url":"/faq/external-drives/what-is-the-efi-partition","category":{"id":"external-drives","title":"External drives"},"subcategory":{"id":"formats","title":"Drive formats"},"question":"What is the hidden EFI partition on my external drive?","alt_questions":["EFI partition external drive Mac","Can I delete the EFI partition?","Small hidden partition on my disk","efi volume mounted on desktop"],"short_answer":"It's a small, normally hidden system partition that GUID-formatted drives carry for starting up a computer. It uses very little space — leave it alone and don't delete or reformat it separately.","answer_markdown":"It's a small system partition that drives formatted with the **GUID Partition Map** scheme carry. It's used when starting up a computer and is normally hidden. It takes very little space; leave it alone, and don't delete or reformat it on its own.\n\nIf it appears in Finder or Disk Utility, it's usually because something mounted it on purpose; ejecting it is harmless. See [why one drive can show as two](/faq/external-drives/why-does-one-drive-show-two-icons).","answer_html":"

It's a small system partition that drives formatted with the GUID Partition Map scheme carry. It's used when starting up a computer and is normally hidden. It takes very little space; leave it alone, and don't delete or reformat it on its own.

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If it appears in Finder or Disk Utility, it's usually because something mounted it on purpose; ejecting it is harmless. See why one drive can show as two.

","answer_text":"It's a small system partition that drives formatted with the GUID Partition Map scheme carry. It's used when starting up a computer and is normally hidden. It takes very little space; leave it alone, and don't delete or reformat it on its own.\n\nIf it appears in Finder or Disk Utility, it's usually because something mounted it on purpose; ejecting it is harmless. See why one drive can show as two.","tags":["efi","partition","guid"],"related":[{"id":"external-drives.why-does-one-drive-show-two-icons","question":"Why does one external drive show up as two drives on my Mac?","url":"/faq/external-drives/why-does-one-drive-show-two-icons"},{"id":"external-drives.disk-utility-only-shows-volumes","question":"Why does Disk Utility only show volumes and not the whole drive?","url":"/faq/external-drives/disk-utility-only-shows-volumes"},{"id":"external-drives.how-do-i-reformat-an-external-drive-to-apfs","question":"How do I reformat an external drive to APFS on a Mac?","url":"/faq/external-drives/how-do-i-reformat-an-external-drive-to-apfs"}],"applies_to":"all","last_reviewed":"2026-10-01","title":"What is the hidden EFI partition on my external drive? — Storage Studio FAQ","description":"It's a small, normally hidden system partition that GUID-formatted drives carry for starting up a computer. It uses very little space — leave it alone and don't delete or reformat it separately.","crumbs":[{"name":"Home","path":"/"},{"name":"FAQ","path":"/faq/"},{"name":"External drives","path":"/faq/external-drives/"},{"name":"What is the hidden EFI partition on my external drive?","path":"/faq/external-drives/what-is-the-efi-partition"}],"jsonld":{"@context":"https://schema.org","@type":"FAQPage","url":"https://storagestudio.us/faq/external-drives/what-is-the-efi-partition","inLanguage":"en","dateModified":"2026-10-01","mainEntity":[{"@type":"Question","name":"What is the hidden EFI partition on my external drive?","alternateName":["EFI partition external drive Mac","Can I delete the EFI partition?","Small hidden partition on my disk","efi volume mounted on desktop"],"acceptedAnswer":{"@type":"Answer","text":"It's a small system partition that drives formatted with the GUID Partition Map scheme carry. It's used when starting up a computer and is normally hidden. It takes very little space; leave it alone, and don't delete or reformat it on its own.\n\nIf it appears in Finder or Disk Utility, it's usually because something mounted it on purpose; ejecting it is harmless. See why one drive can show as two.","url":"https://storagestudio.us/faq/external-drives/what-is-the-efi-partition"}}]},"fragment":"
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External drives · Drive formats

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What is the hidden EFI partition on my external drive?

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Short answer: It's a small, normally hidden system partition that GUID-formatted drives carry for starting up a computer. It uses very little space — leave it alone and don't delete or reformat it separately.

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It's a small system partition that drives formatted with the GUID Partition Map scheme carry. It's used when starting up a computer and is normally hidden. It takes very little space; leave it alone, and don't delete or reformat it on its own.

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If it appears in Finder or Disk Utility, it's usually because something mounted it on purpose; ejecting it is harmless. See why one drive can show as two.

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