Quote:
Originally Posted by haertig
This is why the saying goes: "RAID is not a backup system". RAID stands for "Redundant Array of Independent Disks". So if you experience corruption on one disk, then RAID diligently copies that corruption to the other disks in the array, so you end up with "redundant corruption". RAID is (should be!) used to gain better system uptime or speed. It doesn't do diddly squat for backups. RAID systems need to be backed up just the same as non-RAID systems do. I guess IA didn't know that.
|
RAID, like a Cluster, is simply high availability, not a backup.
And a backup is only local HW/SW failure, not location failure unless there is an off-site copy. Fire, break-ins, subsidence, flood, lightning, truck/car hitting building, bombs, terror, missiles, earthquakes.
Online copies are more about collaboration & sharing than backups.
Mirroring isn't too bad now, but RAID5 rebuild time has got so silly that having backup HDDs offline and copying to a reformatted RAID5 is far faster than a rebuild replacing one 6T drive. The last RAID5 I had was ultra-wide & fast 15000 RPM SCSI drives. Certainly under 5G byte each. HW RAID controller with cache DRAM and battery. But really needed active UPS to avoid serious data loss/corruption on power fail. Prior system was Pentium Pro dual CPU with EISA RAID controller and "hot swap" caddies, only 2G Byte 10,000 RPM SCSI.
Even in late 1990s I got cross with salesman when he pulled out a caddy on our main server as demo. Took hours to rebuid. OTOH the first NT 4.0 cluster (regualar servers with dual external SCSI ports and SCSI extenders as isolator/auto-termination) we had with two sets of mirrored external drives had no issue with pulling power cord out on one server. It did need 4x UPSes!
I gave away my last 8" drive a few years ago, but still have 360K & 1.2M 5.25", both kinds of 3" and 720K and 1.44M 3.5" and one last Mobo with PCI-e and decent CPU with a real floppy port. A USB 3.5" can't read "foreign" formats. Drivers and Emulators for CP/M, DOS, Amstrad PCW and others (not Amiga floppies) on Linux. Some on a much older P4 XP box.
Dumped last PCs with ISA and MFM HDD a few years ago.