3Ware 9550SX-4LP User Guide - Page 191
About Verification, About Verifies of Non-Redundant Units
UPC - 693494960044
View all 3Ware 9550SX-4LP manuals
Add to My Manuals
Save this manual to your list of manuals |
Page 191 highlights
About Background Tasks With the 3ware 9000 series controller, rebuilds on multiple units can take place simultaneously. Rebuilding Units About Verification For the 3ware 9000 series, the verify feature combines verification of redundant units (confirming the validity of the redundant data) and media scans for non-redundant units. (3ware software for the 7000 and 8000 series provided separate features for verify and media scan.) Verification is useful because it can provide early warning of a disk drive problem or failure. For example, if the verification process encounters many error locations, it may be an indication of an excessive number of grown defects on the drive. This allows you to replace drives before they fail. Verifies can be performed through either 3BM (BIOS) or through 3DM. In addition, they can be scheduled to run at preferred times, through 3DM or through the CLI, or can be run automatically during the Verify schedule window, if scheduling and the Auto-verify feature are enabled. For a RAID 1 or RAID 10 unit, a verify compares the data of one mirror with the other. For RAID 5 and RAID 50, a verify calculates RAID 5 parity and compares it to what is written on the disk drive. Verification checks each sector on a drive. This is important, because day-today use of the media may leave many sectors on a drive unused or unchecked for long periods of time. This can result in errors occurring during user operation. Periodic verification of the media allows the disk drive firmware to take corrective actions on problem areas on the disk, minimizing the occurrence of uncorrectable read and write errors. About Verifies of Non-Redundant Units Verification of non-redundant units (single disks, JBODs, spares, and RAID 0 units) read each sector of a drive, sequentially. If a sector can't be read, it is flagged as unreadable, and the next time the controller writes to that location, the drive reallocates the data to a different sector. About Verifies of Redundant Units Verifies of redundant units also read each sector, working from lowest block to highest block. If verification cannot read data in a sector, dynamic sector repair is used to recover the lost data from the redundant drive or drives; this recovered data is written to the problem sector. This forces the drive to reallocate the defective sector with a good spare sector. www.3ware.com 181