Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Hi Mark, Thanks. sorry for weired questions. Problem is that i am not able to make picture in mind how all the stuff is working.i know how DRBD works. but i am not able to relate DRBD with RAID. Can we use DRBD without RAID? Thanks Mark Watts wrote: > > On Tue, 2010-02-02 at 20:51 -0800, Qwerty-1 wrote: >> Hi Mark, >> >> Thanks, what i understood that, to replicate the data locally we need >> RAID >> (RAID helps to decide which data need to be replicated). > > Not quite. > > Hardware RAID (for example) as performed by a dedicated controller, will > take disks and use them in their entirety. The Operating System will see > *one* disk per Logical Disk you create. > > Software RAID can work at either disk level or partition level (where > not all of the disk is used). The Operating System will see all of the > component disks, along with a "RAID device" which you actually format, > mount and store data on. > > In both cases the replication is automatic and total. You don't get to > choose whether data is processed or not. > > RAID is mostly used by folks who want to mitigate the risk of a disk > failure. Some RAID levels use more than one disk and as a side-effect > they may provide more performance. > >> But if we want to >> replicate the date over network then we need DRBD with RAID. In later >> case, >> DRBD will help to transfer data over network (other machine) by making >> TCP >> connectiong and RAID will help to decide which data needs to be >> replicated. >> Please correct me if i am wrong. > > DRBD is another layer in the storage stack, responsible for ensuring > that any data written to a DRBD block device is replicated to a remote > node, thus allowing for certain types of high-availability and/or > fail-over. > > For example, you might have the following (ignoring boot partitions): > > /dev/sda # disk #1 > /dev/sdb # disk #2 > /dev/md0 # Linux software raid-1 mirror > /dev/drbd0 # DRBD Replicated filesystem > > You would then create your filesystem (ext3 or whatever) > using /dev/drbd0. > > Assuming you've setup another node in a similar way, and DRBD is working > correctly, any data you write to /dev/drbd0 will be both replicated to > the remote node, and also mirrored on the local disks. > > In this situation, RAID will be protecting you against disk failure, and > DRBD will be protecting you against machine failure. > > > http://www.drbd.org/users-guide/ is the best place to learn more about > DRBD. > > Regards, > > Mark. > > > -- > Mark Watts BSc RHCE MBCS > Senior Systems Engineer, Managed Services Manpower > www.QinetiQ.com > QinetiQ - Delivering customer-focused solutions > GPG Key: http://www.linux-corner.info/mwatts.gpg > > > _______________________________________________ > drbd-user mailing list > drbd-user at lists.linbit.com > http://lists.linbit.com/mailman/listinfo/drbd-user > > -- View this message in context: http://old.nabble.com/DRBD-Vs-RAID-tp27415521p27434045.html Sent from the DRBD - User mailing list archive at Nabble.com.