Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Hi, On 02/09/2011 06:58 PM, Chris Barnes wrote: > First, I hope this is ok to post this question in this email list... > Secondly, I have been reading the Users Guide at > http://www.drbd.org/users-guide/ - but still have a few "before I start" > type of questions. > > I am wanting to create a high-availability cluster and I *think* DRBD is > what I am looking for. But I'm not quite sure. > > > My *thought* was to use DRBD to mirror the /home filesystem between the > 2 machines - but I have someone working for me that is saying the DRBD > mirrors "entire systems". If he is correct, wouldn't that mean that 2 > computers would require the exact same hardware? it's just not true that DRBD is only for whole-system replication. It's very common to sync only database directories, DFS shares etc. Syncing only /home and keeping everything else up-to-date using other tools like puppet, svn/git etc. makes a lot of sense in many cases! > Or am I not even thinking of DRBD in the correct terms? After all, a > "true high availability cluster" would mean my down time is measured in > seconds, right? I would not have that if all I am mirroring is /home... See above, there are schemes of keeping clustered servers in sync apart from doing block-level storage replication. > My systems (if it matters): > I have one disk array (10TB, Raid5+1) with /home on it's own filesystem > using 7.2T (according to the df command). This machine is in production > and has been in use for a couple of years now. > > I have another system that is completely blank and ready to configure > any way that makes sense. It has 2 250gb drives in a hardware Raid0, > and 8 2tb drives in a hardware Raid5 (currently Raid5+3 - trying to give > me 8tb of space). Uhuh - is this a likely combination of RAID levels? I've read something on this list recently about RAID5 not playing exceptionally well with DRBD performance-wise. Other than that, setting up DRBD on this setup shouldn't pose any problem not covered by the user's guide. Regards, Felix