Fast MySQL Database Backups Without Harming Disk Performance

Why the Answer Is Correct

Option B matches Google's own documented best practice for database backups on Compute Engine: stage the backup on a Local SSD and then push it to a Cloud Storage bucket. Local SSDs are physically attached to the host running the VM and deliver very high IOPS and low latency, so a mysqldump of a specific database finishes quickly, minimizing the time the production MySQL instance spends reading data for the backup. Because the write goes to the local device rather than the boot/data persistent disk, the persistent volumes serving production queries see essentially no additional write pressure, satisfying the "cannot be allowed to impact disk performance" constraint. Once staged, gsutil (or a lifecycle/transfer step) moves the file to Cloud Storage for durability, giving you both speed and long-term, redundant retention.

Why the Other Options Are Wrong

Option A uses persistent disk snapshots, which capture an entire disk image rather than one selected database, and the snapshot read activity is performed against the same persistent disk that serves production traffic — exactly the disk impact the requirement forbids. Option C writes through gcsfuse directly into a Cloud Storage bucket; FUSE-backed writes are network-bound and much slower than local SSD writes, so the backup runs longer and the database remains under sustained read load, which is why commenters flagged "quickly as possible" as the deciding phrase. Option D adds RAID10 volumes plus LVM snapshot plumbing on persistent disks, which adds cost and operational complexity without removing the backup I/O from the production disks, and LVM snapshots still stress the underlying volumes during creation. It also over-provisions storage for every VM when only one database on one instance needs periodic backup.

Community Comment Notes

The community converged strongly on B, with Hannibal1969 explaining that "GCFUSE will write to GCS which is much slower than writing directly to an added SSD" and that it "would also execute reads for a longer period on the production" database. Rathish added that while Local SSD plus gcsfuse could combine speed and direct-to-GCS durability, the phrase "needs to complete as quickly as p..." pushes the answer toward staging on Local SSD. syu31svc and kaush both cited Google's documented guidance to "use the local SSD to stage your backups and then push them to a Cloud Storage bucket." A minority, AD3, argued for C on the grounds that "the mysqldmp provides option to backup specific database," but that confuses the tool choice (mysqldump, used in both B and C) with the storage design, which is what the question actually asks.