mcclnx mcc wrote: > Thank you for answer. The problem is database report "corrupt block", but we even don't know which disk have that "corrupt block" since we use 15 disks Array. > most best practices for raids I've seen suggest using not more than 8 disks in a single RAID 5 or 6... if you need more disks in a single volume, build multiple raid sets then stripe them. For a database, you usually don't want to use raid5 at all, as the random write performance is poor, rather, use raid 1 or 10 (mirror, or striped mirrors). RAID only protects against downtime in case of a drive failure, its no substitute for backups, it won't protect against application based data corruption or much of anything else. A database "corrupt block" is likely -not- a hard drive problem, it means there's a part of one of the database files that has bad data in it. This can be caused by many things, only some of which are hardware related.. Older versions of Oracle did this occasionally, as does MySQL under various stress conditions.