3 ms·
That's not always true: Riverbed Whitewater (now Netapp AltaVault) uses sha256. Source: I wrote that hash-based dedup code
by khc 10y ago
That's not always true: Riverbed Whitewater (now Netapp AltaVault) uses sha256.
Source: I wrote that hash-based dedup code
- sllabres 10y agoVery interesting. Can you tell why SHA256 was chosen? Was it because of the larger hash, or was it a requirement to have a cryptographic secure hash? Do you know how the hash is used in the Netapp in regard to the remark MichaelMoser123 made: "(two blocks are considered equal if the hash is equal - most systems don't care to check for collisions" [...] Is it (overoversimplifed ;): if sha256(a) == sha256(b) { performDedup() [...] Or is a compare added if the hashes found to be identical: if ( sha256(a) == sha256(b) and byteCompare(a) == byteCompare(b) ) { performDedup() [...]
- khc 10y agosha256 was chosen over sha1 because of the larger hash space making collision much less likely. These systems can store 100s of TBs to PBs and at that number of hash blocks you have to start worrying about the birthday paradox.