With few packs a request per pack is fewer requests than 256 listings. On
FTP every listing takes a data connection; the FTP server of the integration
tests has ten passive ports, and 256 listings in a row slowed it down until a
read failed ("Not found: snapshots/...").
Restores and deep verifies requested every blob separately: a new file handle and a seek on
the location each time. They read the blobs of a snapshot in the order they were written, so
the stream of the pack read last now stays open and is read on; a jump backwards, to another
pack, or more than 8 MiB ahead opens the pack again at the offset, as before. On a Hetzner
Storage Box over SMB, restoring 86 MB in 202 files went from 0.78 MB/s to 4.2 MB/s.
Opening a repository lists index/, which holds one file per pack.
StorageBackend::list() checked every entry with is_dir(), and on a
remote storage each check is a round trip. Over SFTP to a Hetzner Storage
Box (33 ms) with a 60 GiB repository, occ backup:run (30 s steps) spent
nearly every step on these requests and uploaded 45 KiB/s; with this
change it uploads 5.8 MB/s. The cost grows with the number of packs.
index/, snapshots/, catalog/ and trash/info/ only ever hold objects:
list them with the new IBackend::listFiles(), one listing without
per-entry checks.
Catch \Exception (storage adapters throw their own exception types) instead
of \Throwable, so an \Error such as a TypeError is not retried and reported
as an unreadable blob.
verifyBlob() caught every exception from loading a blob and counted it as
a failed (corrupted or tampered) blob, so a transient network error during
a deep verify over WebDAV looked like data corruption. Read the range
separately, retry it, and report a read that keeps failing as unreadable
with its error; only a blob that was read but does not decrypt or match
its id counts as failed.
Repository::verify(): every blob a snapshot's files and database dump reference must be in a
freshly re-downloaded, re-authenticated index (never trusted from the local cache, same reasoning
as prune()) and have its pack still present on the location -- shallow, cheap, no blob content
read, catches a deleted pack, a tampered/rolled-back index, or a database manifest that went
missing (reported as a failure, not silently skipped). With $deep, each blob is also downloaded
and decrypted, same as loadBlob() already does on every real read (AEAD authentication tag,
content hash against its blob id), done here deliberately for everything in the snapshot rather
than waiting for it to come up during an actual restore. A blob referenced by more than one file
is only checked once; pack presence is cached per pack, not re-checked per blob.
occ backup:verify <target> <snapshot> [--deep], meant to run periodically (cron, a sample of
recent snapshots), per PLAN.md's "Verificatie: periodiek checksums controleren, steekproef-restore".
The lease covering the audit is refreshed roughly every half of its TTL while blobs are checked,
rather than relying on a single long-lived lease like the other new phase-2 commands do.
Verified against a real S3-backed 1.4 GiB / 603-blob snapshot (shallow: instant; --deep: ~28s,
fully decrypted) in addition to the new unit tests and the roundtrip.sh addition (shallow and deep
on a snapshot with real, varied file sizes, now covered on every CI matrix combination).
Local review (Codex) on the first pass found three real issues, all fixed: a missing database
manifest was silently skipped instead of reported; shallow verification trusted the (possibly
stale or unauthenticated) local index cache instead of re-checking the authenticated index on the
location; and the lease had no refresh, so a --deep audit of a very large snapshot could outrun
its TTL and run unprotected against a concurrent prune.
dillard