G
gus bjorklund
Guest
> On Aug 15, 2019, at 7:05 AM, frank.meulblok wrote: > > Update from Progress Community > > frank.meulblok > > If you want to sum up the above in more non-technical terms: > > 1. RAID-5 sacrifices write speed by design. > > 2. Every change to your data will get written to disk at least 3 times (persistent storage because that's what a DB is for, before-image and backup in case something goes wrong), often 4 times (after imaging). If you want to get rid of those extra writes: DON'T. They're your basic safeguard to ensure you can recover when something goes wrong. > > Conclusion: RAID-5 guarantees your database performace will suffer when you reach a certain level of create-update-delete workload. > > 3. When something goes wrong and you need to recover, restoring the system will cause a lot of disk writes that need to happen as fast as possible to minimize downtime. Because downtime only costs money and doesn't gain any. > > Conclusion: RAID-5 will turn any disaster into a bigger disaster. > Restating no. 3: RAID-5 performs worst when you need it most. Disaster reecovery delays will cost lots of money. and adding no. 4: 4. Salesperson's lie: "Yes, those problems were common with some of the early RAID-5 systems. They have been solved in our (modern, proprietary, special) storage arrays.". This is not even close to true.
Continue reading...
Continue reading...