4 ms·
Is that a single address space system or merely two systems with db2 databases and disk volumes on a SAN in replication? I think it's the latter. 100 miles wil
by wolf550e 7y ago
Is that a single address space system or merely two systems with db2 databases and disk volumes on a SAN in replication? I think it's the latter.
100 miles will add 5ms (round trip) to your disk flush on commit. So a system like this has the sequential and random IO latencies of a RAID of SSDs but the flush (database commit) times of a 15K RPM spinning rust disk. People lived with mechanical disks, it's ok.
Sync disk replication (in one direction) over a fiber line is not an exclusive feature. Having both sides be active, instead of active and hot standby requires some smarts from the software, but modern distributed databases do that, and if you're careful you can get far with batch sync jobs.
- chx 7y agoIt might be just storage as it was brought up as an example of how subsystems of mainframes are essentially their own world and a single disk or distributed volumes over a long distance are presented the same to the rest of the system. In the Linux world DRBD does something similar (just much simpler). The point, however, is that the software knows nothing about this being distributed.