Hi Prasenjit Thank you for your reply.
However, I doubt that incremental backup can reduce RTO. I think the demerit of incremental backup is to take longer repair time rather than without incremental backup. Because I've compared the repair time of two cases like below. (a) snapshot(10GB, full repaired) + incremental backup(1GB) (b) snapshot(10GB, full repaired) Each case consists of 3 node cluster, replication factor is 3 and total data size is 12GB/node. And we assume one node got failure then we restore the node. The result showed that case (b) is faster than case (a). The repair process of the token ranges included in incremental backup was very slow. However, the just transferring replicated data from existing nodes to repairing node is faster than repair. So far, I think Pros and Cons of incremental back is as following: - Pros (There are already agreed by you) - It allows storing backups offsite without transferring entire snapshots - With incremental backups and snapshots, it can provide more recent RPO (Recovery Point Objective) - Cons - It takes much longer repair time rather than without incremental backup (longer RTO) Is it correct understand? I would appreciate you can give me any advice or ideas if I was misunderstanding. Regards, Satoshi On Fri, Jul 15, 2016 at 1:46 AM, Prasenjit Sarkar <prasenjit.sar...@datos.io > wrote: > Hi Satoshi > > You are correct that incremental backups offer you the opportunity to > reduce the amount of data you need to transfer offsite. On the recovery > path, you need to piece together the full backup and subsequent incremental > backups. > > However, where incremental backups help is with respect to the RTO due to > the data reduction effect you mentioned. The RPO can be reduced only if you > take more frequent incremental backups than full backups. > > Hope this helps, > Prasenjit > > On Wed, Jul 13, 2016 at 11:54 PM, Satoshi Hikida <sahik...@gmail.com> > wrote: > >> Hi, >> >> I want to know the actual advantage of using incremental backup. >> >> I've read through the DataStax document and it says the merit of using >> incremental backup is as follows: >> >> - It allows storing backups offsite without transferring entire snapshots >> - With incremental backups and snapshots, it can provide more recent RPO >> (Recovery Point Objective) >> >> Is my understanding correct? I would appreciate if someone gives me some >> advice or correct me. >> >> References: >> - DataStax, "Enabling incremental backups", >> http://docs.datastax.com/en/cassandra/2.2/cassandra/operations/opsBackupIncremental.html >> >> Regards, >> Satoshi >> > >
