Keep three copies on two kinds of storage, with one off-site, and encrypt any copy that leaves your hands. For a 30× genome, plan on a few hundred gigabytes if you keep the raw reads, or about a gigabyte if you keep only the VCF.
Check every copy against a checksum so you know it isn't corrupted.
What you're actually storing
A whole genome order can come with three kinds of raw file, plus reports. Sizes vary a lot with sequencing depth, read length and the provider's pipeline, so treat these as planning ranges for a 30× human genome, not exact figures:
| File | What it is | Typical size (30×) |
|---|---|---|
| FASTQ | Raw reads straight off the sequencer | ~100–200 GB |
| BAM | Reads aligned to a reference genome | ~80–100 GB |
| CRAM | A smaller, reference-based alternative to BAM | ~30–60 GB |
| VCF | The list of places your DNA differs from the reference | ~1 GB |
Ranges are from Lab Manager’s NGS storage sizing guide. Your own files may be bigger or smaller; check the sizes on the download page before you buy drives.
Which files matter most? The FASTQ files are the raw material: everything else can be regenerated from them with future tools. The BAM saves you from re-aligning. The VCF is tiny and is what most analysis tools actually read. If space is tight, the VCF is the one copy you should keep everywhere. Not sure which files you have? The file inspector identifies the format locally, without uploading anything.
The 3-2-1 plan, applied to a genome
Standard backup advice is three copies of anything important, on at least two different kinds of storage, with at least one copy somewhere else. For genome files that looks like this:
Copy 1: a local drive you control
An external SSD or hard drive with comfortable headroom over your total file size. Leave space for analysis outputs later. This is your working copy.
Copy 2: a second local copy
A second external drive, or a home NAS if you already run one. A RAID volume protects against one disk failing, but not against accidental deletion or ransomware, so use a NAS that keeps snapshots or treat it as one copy, not two. A second drive kept at a family member’s house also doubles as your off-site copy.
Copy 3: off-site, usually cloud
Cold or archive storage tiers suit genome files well, because you rarely need to restore them quickly. Things to compare before you choose:
- Retrieval time. AWS S3 Glacier Deep Archive, for example, says data is retrievable within 12 hours, with options ranging from 12 to 48 hours.
- Fees to get data back out. Some providers charge for downloads (egress); Cloudflare R2, for example, says it charges no egress fees.
- Minimum storage periods and per-request fees on archive tiers.
We don’t list prices here because they change. Use each provider’s own pricing calculator with your actual file sizes.
Encrypt before it leaves your hands
A genome is permanent, identifying information about you and your relatives. Encrypt any copy you don’t physically control. The simplest routes:
- Encrypted drives: FileVault-style full-disk encryption on your computer, and an encrypted format (APFS Encrypted on a Mac, BitLocker on Windows editions that have it, LUKS on Linux) on external drives.
- Encrypt before uploading: a tool such as rclone’s crypt remote encrypts files on your machine before they reach the cloud, so the provider only stores scrambled data.
- Keep the keys safe. Lose the password or recovery key and the data is gone for good. Store it in a password manager and somewhere offline.
Check every copy
A large download or copy can be silently corrupted. A checksum is a short fingerprint of a file; if two copies give the same checksum, they’re identical. If your provider publishes checksums, compare against those. If it doesn’t, make your own right after downloading and keep them in a text file next to the data:
# macOS
shasum -a 256 sample.bam
# Linux
sha256sum sample.bam
# Windows (PowerShell)
Get-FileHash sample.bam -Algorithm SHA256Run the same command on each backup copy and compare. If they don’t match, copy again from a good source. For BAM and CRAM files, samtools quickcheck is a fast extra check that the file isn’t truncated, if you have samtools installed.
Label it for future you
Keep each order in one clearly named folder (raw, aligned, variants, reports) and add a plain text README with:
- the provider and order date, and the account it was ordered under;
- the reference genome build the files use (GRCh37 or GRCh38). The file inspector can often detect it from a VCF header;
- where each backup copy lives, and where the checksums are.
Five years from now that note will save you an afternoon.
Commercial option · affiliate link
Want the whole genome and every raw file?
Dante Labs sequences the whole genome at 30× and lets you download the raw BAM, FASTQ and VCF files.
Check Dante’s current offer →Our code GENOME may apply; codes may not combine with sitewide sales. Why this is an affiliate link.
What not to do
- Don’t rely on one drive. Every drive fails eventually. One copy is a delay, not a backup.
- Don’t rely on the provider’s portal. Companies are sold and policies change, as 23andMe customers saw after its 2025 bankruptcy and sale. Download your files while you can.
- Don’t put unencrypted genome files in everyday cloud folders that sync to many devices.
- Don’t upload to genealogy or analysis sites casually. Check the privacy checklist first, especially law-enforcement and matching settings.
Common questions
How much space do whole genome raw files take?
For a 30× genome, planning ranges are roughly 100–200 GB of FASTQ, 80–100 GB of BAM and about 1 GB of VCF. Your provider's files may differ, so check the download sizes.
Which file should I keep if space is limited?
Keep the VCF everywhere, since it's small. Keep the FASTQ (or BAM/CRAM) on at least one good backup if you want to reanalyse with future tools.
Is cloud storage safe for genome data?
It can be, if you encrypt the files before upload and keep the key yourself. Then the provider only holds scrambled data.
How do I know a copy isn't corrupted?
Compare checksums. Run sha256sum (Linux), shasum -a 256 (macOS) or Get-FileHash (Windows) on the original and each copy; matching values mean identical files.
Does my provider keep my files forever?
Don't assume so. Retention policies vary and companies change hands. Keep your own copies.
Keep going
Sources
Rewritten October 25, 2026. File-size ranges are planning figures from Lab Manager; cloud retrieval and egress details are from AWS and Cloudflare documentation checked the same day. We removed earlier figures (a 900 GB total, per-provider prices and a claim that Dante supplies MD5 checksums) that we could not verify.
- Lab Manager: How big is NGS data? Sizing storage for your sequencing volume
- AWS: Amazon S3 Glacier storage classes
- Cloudflare R2 pricing
- Microsoft: Get-FileHash
- samtools quickcheck manual
Educational content, not medical advice. A genetic result is information, not a diagnosis; for anything medically important, talk to a qualified clinician or genetic counselor. Some outbound links are affiliate links; see the disclosure.