How are bad sectors detected and handled by mainframe-class computer...
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From: Man-wai Chang to The Door (24000bps) on 16 Feb 2010 04:56 .... compared to a typical PC hard disk? -- @~@ Might, Courage, Vision, SINCERITY. / v \ Simplicity is Beauty! May the Force and Farce be with you! /( _ )\ (x86_64 Ubuntu 9.10) Linux 2.6.32.8 ^ ^ 17:55:01 up 1 day 2:45 0 users load average: 1.10 1.10 1.06 ���ɶU! ���B�F! ������! ������! �����T! ���۱�! �ЦҼ{� (CSSA): http://www.swd.gov.hk/tc/index/site_pubsvc/page_socsecu/sub_addressesa
From: SteveH on 16 Feb 2010 05:50 Man-wai Chang to The Door (24000bps) wrote: > ... compared to a typical PC hard disk? Presumably by having redundant drives. fault tolerance and backups. -- SteveH
From: Benjamin Gawert on 17 Feb 2010 01:10
* Man-wai Chang to The Door (24000bps): > .... compared to a typical PC hard disk? Basically the same. Bad sectors are not detected by the computer, they are detected by the hard drive's controller. Every disk has bad sectors, it only becomes a problem when there are no spare sectors left to relocate data. In this case a SMART warning/error is issued to the hard drive controller. Mainframe-class computers don't have internal disks, they use storage systems connected over network-like interfaces like Fibre Channel. Everything which has to do with disk management is done in the storage systems which usually use hardware RAID for redundancy and availability, the available storage space is fully transparent to the computer (it doesn't "see" hard drive defects). Hardware RAID controllers like HP Smart Array controllers which are used in standard servers (HP ProLiants) work similarly, they work fully transparent to the operating system. If a SMART warning/error is issued by a disk drive in a mainframe storage system or on a hardware RAID in a standard server the disk is flagged as faulty and replaced by the administrator, after which a rebuild cycle starts (which again is fully transparent to the computer itself). On a desktop PC, if a SMART warning/error occurs, the user will get a warning at bootup if the BIOS has proper SMART support. On a Mac, the user will have to look into the hard disk utility or use other utilities to check the SMART status. As not all errors are flagged over SMART, storage systems and hardware RAID controllers regularly do consistency checks of their hard drives, too. Benjamin Benjamin |