You are quite correct and it is something that I have pointed out several times to rather puzzled managers. We don't sell a service but for most systems the RPO is 24 hours. I have pointed out that for many systems where they take a FULL backup on Friday, and Cumulative Incremental on Mon, Tue, Wed, Thu only, that the worst case RPO at say 18:00 Monday, is all the way back to the Friday.
You cannot do an RPO of 24 hours with backups every 24 hours. Oh, and please add the time it takes for the backup tapes to actually be collected and taken offsite, otherwise for site DR you may lose those tapes also - either physically or even worse, behind the police "Do not Cross" tape. In the latter case you may have problems accessing some systems to shut them down so you can fail them over.... Best plan would be something like weekly full, daily cumulative, x hourly differential. The last could be to disk and replicate offsite, e.g.PureDisk STU. Cheaper still is what you tried, don't offer 24 hour RPO! William D L Brown From: veritas-bu-boun...@mailman.eng.auburn.edu [mailto:veritas-bu-boun...@mailman.eng.auburn.edu] On Behalf Of JC Cheney Sent: 16 July 2010 10:09 To: Dean; veritas-bu@mailman.eng.auburn.edu Subject: Re: [Veritas-bu] How to implement a 24 hour RPO with a traditionalbackup system. Snapshot client? I guess you'd still be 24hrs + time to take the snap but that should be negligible... From: veritas-bu-boun...@mailman.eng.auburn.edu [mailto:veritas-bu-boun...@mailman.eng.auburn.edu] On Behalf Of Dean Sent: 16 July 2010 05:54 To: veritas-bu@mailman.eng.auburn.edu Subject: [Veritas-bu] How to implement a 24 hour RPO with a traditionalbackup system. Hi folks, This is in no way NetBackup specific, but I'm wondering if some of the smart people on this mailing list might have some thoughts. The company I work for have several service classes for Disaster Recoverability, mainly based on RPO (Recovery Point Objective). RPO refers to the amount of data loss that the company are willing to sacrifice in the case of a disaster. The customer is charged higher rates for the higher service classes. Platinum level service class means zero data loss, so that basically means synchronous cross-site disk mirroring for the applications. Gold level is 2 hours, so we use asynchronous disk mirroring, and/or ship the archive logs to the other site every 30 minutes or so. Silver is 24 hours. The large majority of our backup clients fall into this category. Silver class is all based on tape backup/recovery. It's the traditional overnight backup to tape (or disk, VTL, whatever).... fulls on the weekend, incrementals on weeknights. But one of our clients has questioned this worst-case 24 hour RPO, and their query is quite valid. Here is an example: There is a system with 24 hour RPO that we backup every night at 6PM. The backup takes one hour. So, if a disaster occurs at 6:59 PM, before tonight's backup completes, we have to restore from the previous night's backup. But, really, that backup is only consistent as of 6PM the previous night, when the backup *started*. That means our worst case RPO is actually 25 hours. I know this can be fixed with disk mirroring, but I'm looking for ways around this using purely "traditional" tape based (or disk) backup. If we're going to mirror all these systems, we'd be effectively moving them all to the Platinum DR class, and the customer is not willing to pay for that. To do it with a traditional daily backup regime, we'd have to ensure that each day's backup completed less than 24 hours before the previous day's backup started, which means the backup window would constantly rotate throughout the day. Obviously that's not realistic. The easy solution is to adjust the SLA to say that the RPO is "24 hours, plus the elapsed time of your backup", but the customer will not accept that. We could also do something like running two backups a day, but obviously that will double the resources we need for our backup infrastructure, and I don't think the customer would be happy with all their servers grinding to a halt when the backups kick off in the middle of the day. Has anyone else worked through this issue? Any input appreciated :) Thanks, Dean ----------------------------------------------------------- This e-mail was sent by GlaxoSmithKline Services Unlimited (registered in England and Wales No. 1047315), which is a member of the GlaxoSmithKline group of companies. The registered address of GlaxoSmithKline Services Unlimited is 980 Great West Road, Brentford, Middlesex TW8 9GS. -----------------------------------------------------------
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