Thanks, the image is visible now. > Since I wanted to open this for discussion, did not consider placing it in *hbase/dev_support/design-docs*.
Definitely, only after we come to concrete conclusion with the reviewer, we should open up a PR. Until then this thread is anyways up for discussion. On Mon, 25 Jan 2021 at 1:58 PM, Mallikarjun <mallik.v.ar...@gmail.com> wrote: > Hope this link works --> https://ibb.co/hYjRpgP > > Inline reply > On Mon, Jan 25, 2021 at 1:16 PM Viraj Jasani <vjas...@apache.org> wrote: > > > Hi, > > > > Still not available :) > > The attachments don’t work on mailing lists. You can try uploading the > > attachment on some public hosting site and provide the url to the same > > here. > > > > Since I am not aware of the contents, I cannot confirm right away but if > > the reviewer feels we should have the attachment on our github repo: > > hbase/dev-support/design-docs , good to upload the content there later. > For > > instance, pdf file can contain existing design and new design diagrams > and > > talk about pros and cons etc once we have things finalized. > > > > > Since I wanted to open this for discussion, did not consider placing it in > *hbase/dev_support/design-docs*. > > > > > > On Mon, 25 Jan 2021 at 12:13 PM, Mallikarjun <mallik.v.ar...@gmail.com> > > wrote: > > > > > Attached as image. Please let me know if it is availabe now. > > > > > > --- > > > Mallikarjun > > > > > > > > > On Mon, Jan 25, 2021 at 10:32 AM Sean Busbey <bus...@apache.org> > wrote: > > > > > >> Hi! > > >> > > >> Thanks for the write up. unfortunately, your image for the existing > > >> design didn't come through. Could you post it to some host and link it > > >> here? > > >> > > >> On Sun, Jan 24, 2021 at 3:12 AM Mallikarjun <mallik.v.ar...@gmail.com > > > > >> wrote: > > >> > > > >> > Existing Design: > > >> > > > >> > > > >> > > > >> > Problem 1: > > >> > > > >> > With this design, Incremental and Full backup can't be run in > parallel > > >> and leading to degraded RPO's in case Full backup is of longer > duration > > esp > > >> for large tables. > > >> > > > >> > Example: > > >> > Expectation: Say you have a big table with 10 TB and your RPO is 60 > > >> minutes and you are allowed to ship the remote backup with 800 Mbps. > And > > >> you are allowed to take Full Backups once in a week and rest of them > > should > > >> be incremental backups > > >> > > > >> > Shortcoming: With the above design, one can't run parallel backups > and > > >> whenever there is a full backup running (which takes roughly 25 hours) > > you > > >> are not allowed to take incremental backups and that would be a breach > > in > > >> your RPO. > > >> > > > >> > Proposed Solution: Barring some critical sections such as modifying > > >> state of the backup on meta tables, others can happen parallelly. > > Leaving > > >> incremental backups to be able to run based on older successful full / > > >> incremental backups and completion time of backup should be used > > instead of > > >> start time of backup for ordering. I have not worked on the full > > redesign, > > >> and will be doing so if this proposal seems acceptable for the > > community. > > >> > > > >> > Problem 2: > > >> > > > >> > With one backup at a time, it fails easily for a multi-tenant > system. > > >> This poses following problems > > >> > > > >> > Admins will not be able to achieve required RPO's for their tables > > >> because of dependence on other tenants present in the system. As one > > tenant > > >> doesn't have control over other tenants' table sizes and hence the > > duration > > >> of the backup > > >> > Management overhead of setting up a right sequence to achieve > required > > >> RPO's for different tenants could be very hard. > > >> > > > >> > Proposed Solution: Same as previous proposal > > >> > > > >> > Problem 3: > > >> > > > >> > Incremental backup works on WAL's and > > >> org.apache.hadoop.hbase.backup.master.BackupLogCleaner ensures that > > WAL's > > >> are never cleaned up until the next backup (Full / Incremental) is > > taken. > > >> This poses following problem > > >> > > > >> > WAL's can grow unbounded in case there are transient problems like > > >> backup site facing issues or anything else until next backup scheduled > > goes > > >> successful > > >> > > > >> > Proposed Solution: I can't think of anything better, but I see this > > can > > >> be a potential problem. Also, one can force full backup if required > WAL > > >> files are missing for whatever other reasons not necessarily mentioned > > >> above. > > >> > > > >> > --- > > >> > Mallikarjun > > >> > > > > > >
