Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Exactly. I was trying to replicate /boot with 'meta-data internal' which would cause it to die being that the space wasn't available. I am slowly getting my head around the whole process. However, I can't seem to mount the drbd device. I edited my fstab from /dev/hda2 / ext3 defaults 1 1 to /dev/drbd0 / ext3 defaults 1 1 and it does not like it. When I try to start drbd manually using 'service brbd start' or 'drbdadm up all', I get an error that /dev/hda2 is already mounted. So I am a bit confused as to how to actually mount the /dev/drbdx device. Essentially I want the root file system to be identical between two boxes for a failover situation. Am I headed in the right direction? Thanks again for everyone's help. Once I am done with this, I am very tempted to write a new HowTo for real novices such as myself. ________________________________________ Chip Burke ________________________________________ -----Original Message----- From: Clive Eisen [mailto:clive at serendipita.com] Sent: Thursday, January 05, 2006 9:03 AM To: cburke at innova-partners.com Cc: drbd-user at lists.linbit.com Subject: Re: [DRBD-user] meta-disk Only if you told drbd to put the meta data on /boot Not A Good Idea (tm). Yes you mount the /dev/drbdx devices If you are using linux-ha, you allow that to do the mounting. -- Clive Chip Burke wrote: >Thank you very much for the very complete answer. I think I know what the >issue is then. I have a separate /boot partition and it is only 100MB. The >fact that it is only 100MB would not allow a 128MB file to be created. That >makes sense. > >My next question is, after read the linux-ha docs, it hints at this, but is >not very explicit... In fstab am I to mount the new /dev/drbdx devices that >are created instead of the normal /dev/hdx devices? > >Thank you so much for your help, > >________________________________________ >Chip Burke >________________________________________ > > >-----Original Message----- >From: drbd-user-bounces at lists.linbit.com >[mailto:drbd-user-bounces at lists.linbit.com] On Behalf Of Chris Procter >Sent: Thursday, January 05, 2006 6:00 AM >To: drbd-user at linbit.com >Subject: Re: [DRBD-user] meta-disk > >On Wednesday 04 January 2006 20:07, Chip Burke wrote: > > > >>I think I am missing something very basic. Do I need to create a partition >>on the system specifically for the meta-data or something else? I have >> >> >read > > >>the drbd.conf notes about 10 times and I really don't understand what they >>mean. >> >> > >As with all good questions the answer is "it depends". > >DRBD needs to store 128MB of metadata some where on the system to store the >list of which blocks have changed (its stored on disk so it persists across >reboots). This metadata can be stored in one of two places. > >It can be stored on the partition you are replicating (termed "internal" >metadata) in which case it basically takes over the last 128MB of the >partition, reducing the space you have to store data in and overwriting and >data that is already stored there. This is good if you are starting fresh >and >can overwrite the diskspace without risking the data or dont have room to >create a separate partition. >For this you put: >meta-disk internal; >in the drbd.conf for each machine (the "on [hostname]" section). > >Alternatively you can store the metadata on a separate partition ("external" > >metadata) in which case (obviously) you need to create a partition to use. >This partition needs to be at least 128MB for each DRBD device you are using > >and is setup in the drbd.conf file as: >meta-disk [devicename] [[offset]]; >e.g. >meta-disk /dev/hde5 ; > >The number in brackets is an offset within the partition, so the above will >use the first 128MB of the /dev/hde5 partion to store meta data, you could >then set up another drbd device (/dev/drbd1 say) with >meta-disk /dev/hde5 ; >which would use the second 128MB (obviously the partition would need to be >at >least 256MB in size). You would then have the meta data for /dev/drbd0 in >0-127MB and for /dev/drbd1 in 128-256MB on /dev/hde5 > >There are probably performance reasons for using one over the other, and >there >are certainly issues with diskspace (if you dont have space to create a >seperate partion the internal is the way forward for example). In theory you > >could configure drbd to use internal metadata on one machine and external >for >the same device on the other machine. If you do this however you're on your >own :-) > >Your error message implies that the meta-disk you are using is less then >128MB >in size. I'm not sure if it defaults to something if you dont define it in >drbd.conf so its worth checking to make sure it is explicitly defined to >something sensible. > >Thats the way I understand it anyway, hope it helps. > >chris >_______________________________________________ >drbd-user mailing list >drbd-user at lists.linbit.com >http://lists.linbit.com/mailman/listinfo/drbd-user > > >_______________________________________________ >drbd-user mailing list >drbd-user at lists.linbit.com >http://lists.linbit.com/mailman/listinfo/drbd-user > >