Linux - NewbieThis Linux forum is for members that are new to Linux.
Just starting out and have a question?
If it is not in the man pages or the how-to's this is the place!
Welcome to LinuxQuestions.org, a friendly and active Linux Community.
You are currently viewing LQ as a guest. By joining our community you will have the ability to post topics, receive our newsletter, use the advanced search, subscribe to threads and access many other special features. Registration is quick, simple and absolutely free. Join our community today!
Note that registered members see fewer ads, and ContentLink is completely disabled once you log in.
Distribution: RHEL, CentOS, Debian, Oracle Solaris 10
LVM mirroring at a minimum requires 3 physical volumes.
2 volumes for the both sides of the mirror and a volume for log.
The way mirroring works in LVM is that the system creates arbitrary data blocks(e.g. 512 KB in size) and it's these individual blocks that are kept in sync across the drives. The log is the essential mechanism for the system to keep the data of sync status in across reboots, hence it can't be on any of the mirrored drives. You can also configure the system to keep the log in the RAM, but this means that your drives will have to be synced every time your system's rebooted (which's a VERY bad idea, because syncing is among the slowest LVM/RAID operations ever).