Revive a deleted record

1

Hi,

After delete a record, Aerospike writes tombstone, if we use ‘durable delete’ policy.

  1. After how long actually the record gets deleted?
  2. Is there any way to revive the record that is deleted accidentally?
  3. For how long the deleted records are retained?

Thanks Venkata

2

This is a good primer for tombstones: How to recover tombstones faster

It isn’t a fixed amount of time, it depends on many factors which include how many copies of the deleted record are still on the disk in live blocks or free blocks that haven’t been overwritten.

The “Tomb Raider” is a periodic device scan that does a mark and sweep style GC of tombstones. Only when the disk scan finds that a digest no longer exists on any device does Aerospike know that the record is truly removed from the local machine. At which time the tombstone may be removed if eligible based on tomb-raider-eligible-age .

If a node was taken offline prior to a record being deleted and that node returns to the cluster after tomb-raider-eligible-age seconds then that returning node could resurrect the record. To prevent this, you should zeroize a node when it has been down for more then tomb-raider-eligible-age seconds.

3

Is there any way to revive a record that is deleted accidentally with (durable delete) option? If the record is not yet reclaimed by tomb-raider.

4

No, you cannot recover a record that has been durably deleted. BTW, the tomb-raider doesn’t remove data, it is just checking if the record has been overwritten by other processes - such as defrag writes, client writes, replica writes, etc.