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= Optimal LUKS Encryption Sector Size = | = Optimal LUKS Encryption Sector Size = | ||
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Revision as of 12:03, 24 June 2021
Optimal LUKS Encryption Sector Size
Summary
Autodetect optimal encryption sector size during Fedora installation with LUKS/dm-crypt encryption. On devices with 4K (physical) sector size this will
Owner
- Name: Ondrej Kozina, Vojtech Trefny
- Email: okozina AT redhat.com, vtrefny AT redhat.com
Current status
- Targeted release: Fedora Linux 35
- Last updated: 2021-06-24
- FESCo issue: <will be assigned by the Wrangler>
- Tracker bug: <will be assigned by the Wrangler>
- Release notes tracker: <will be assigned by the Wrangler>
Detailed Description
Anaconda (libraries Anaconda uses for storage configuration) currently sets sector size for LUKS devices to 512 regardless of actual physical sector size of the underlying disk device. Latest cryptsetup release added an option to let cryptsetup automatically detect the optimal sector size based on the (physical) sector size of the backing device. By using this new option we can make sure that Anaconda uses the optimal sector size for newly created LUKS devices during installation. This means we will use sector size of 4096 for devices with 4k physical sector size increasing IO performance with these devices.
Feedback
Benefit to Fedora
Scope
- Proposal owners: Changes for both cryptsetup and libblockdev (low level storage library used by Anaconda) are already merged (cryptsetup) or submitted (libblockdev) upstream. We only need to package new versions of these two projects for Fedora 35.
- Other developers: No work from other developers is needed.
- Release engineering: #Releng issue number
- Policies and guidelines: N/A (not needed for this Change)
- Trademark approval: N/A (not needed for this Change)
- Alignment with Objectives:
Upgrade/compatibility impact
Upgraded systems will not be affected by this change, this affects only new LUKS containers created during Fedora installation.
How To Test
Disk with 4k physical sectors is required for testing this change. You can check block size of your drive using blockdev from util-linux package:
# blockdev --getpbsz /dev/nvme0n1 4096
This can be also tested in a virtual machine. You can configure any disk to appear as a 4k block size disk in libvirt by adding following option to the disk XML specification:
<blockio logical_block_size="4096" physical_block_size="4096"/>
Install Fedora with disk encryption enabled. Using automatic partition with Encrypt my data enabled is enough for testing.
In the installed system use cryptsetup luksDump /dev/<device> to check that correct sector size was selected for your device (4096 for disks with 4096 physical sector size):
# cryptsetup luksDump /dev/nvme0n1p1
LUKS header information
Version: 2
...
Data segments:
0: crypt
offset: 16777216 [bytes]
length: (whole device)
cipher: aes-xts-plain64
sector: 4096 [bytes]
User Experience
Dependencies
None.
Contingency Plan
- Contingency mechanism: Keep existing behaviour (512 sector size for all devices)
- Contingency deadline: Beta Freeze
- Blocks release? No