RAID 1 Synchronization

[pristanovic]

We have a pair of IBM 360 nodes clustered on MS Windows with a shared SCSI based EXP300. We use MS Clustering and IBM ServeRAID with SCSI controlelrs. Within the EXP300 we have 6 pairs of RAID 1 drives spanned as a single logical drive, i.e. RAID 10 configuration. On every failover of nodes ServeRAID synchronizes drives with each pair one by one. Synchronization of a pair of drives takes about 1 hour, i.e. about 6 hours for 6 pairs! During this time the performance of the system is so degraded that it is practically impossible to use it. Also, the synchronization triggers periodically with the same devastating effect on performance. Any clue why would ServeRAID synchronize RAID 1 pairs? Any way to disable this ServeRAID "feature"?

 

[catorze]

Synchronization occurs for data integrity. Normally this occurs at a low priority when cycles are available. If it happens during failover, it would seem that you have enough traffic to prevent it from happening routinely during idle time. Althoug disabling it would be efficient, it would really suck when you corrupt your data. Perhaps a reconsideration of your RAID strategy is in order?