On 06/28/10 7:53 PM, Emmanuel Noobadmin wrote:
The only problem is their HA is commercial only and costs more than the entire hardware budget I've got for this. Crucially, it relies on a failover/heartbeat kind of arrangement. According to some sources, the failover delay of a few seconds will cause certain services/apps to fail/lock up. Not an issue for the immediate need but will be a major no no for the other project I have in the pipeline.
Which was why I was thinking of MD raid 1 on the application server site: no failover delay if one of the data server fails to respond to respond in time.
ISCSI gets REAL sketchy on network failures. it takes at least several TCP timeouts before it gives up and returns an error. I do hope both storage servers have ECC so you're not mirroring a soft bit error at an inopportune time (Solaris ZFS would cope gracefully with this, but likes iscsi timeouts even less than dmraid)