Why is this "unsettling?" It's a whole lot better than having your data on one physical volume and losing everything with the failure of just _one_ device.
The type of RAID you're talking about is essentially a form of parity checking. The bits of the data are spread across multiple volumes, and the "parity" information is what is used to rebuild the data in the event of a device failure. If you lose more "bits" (devices) than the parity algorithm can withstand, then you lose your data. Backups are still required in a RAID environment. Nothing is ever going to eliminate the need for that. If you're using modern disk storage, that unit is already a RAID device. Using software RAID on top of that can have some important advantages, but for purposes of data integrity is probably not needed. In most cases LVM will do what you want, and do it better. Mark Post -----Original Message----- From: Dennis Wicks [mailto:[EMAIL PROTECTED]] Sent: Monday, February 10, 2003 1:57 PM To: [EMAIL PROTECTED] Subject: raid question Greetings; (Posted to LINUX-390 and debian-s390 lists) I came across an unsettling bit of info a while back. I was told that if you lose one volume of a raid set you can replace and the data will get rebuilt, but if you lose a second volume before you get the first one rebuilt you will lose all the data -- irretrievably! Is this true? Is there any reasonable way to get around it? Is there a reasonable alternative to raid? As always, Many TIA! Dennis -- Dennis G. Wicks Systems Programmer [EMAIL PROTECTED] Communications Data Group Tel: (217)355-7117 Fax: (217)351-6994 102 S. Duncan Rd. Champaign, IL 61822
