I tried to build ‘hello’ twice, and the following error occurred each
time:

stripping binaries in "/nix/store/hl8khv4qip9nwbm1qm93irbz9has4wrd-gcc-cross-boot0-4.7.3/bin" with "strip" and flags ("--strip-debug")
phase `strip' succeeded after 17 seconds
error (ignored): aborting transaction: cannot rollback - no transaction is active
guix package: error: build failed: committing transaction: disk I/O error

I guess something is wrong with my system, what should I check?