Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
/ 2005-09-12 15:09:22 +0000 \ Barry Price: > Hi, > > We're looking at DRBD as a way to get a live-backup going on our database > server. It's an 8cpu SCSI-fired RAID1+0 monster with 16Gb RAM, and it's usually > very, very busy. > > The database server is PostgreSQL 8, and consists of over 10,000 tables with up > to 2,000 connections, processing several hundred queries per second. DRBD looks > like exactly what we need, but the testimonials I've seen have all been on > rather smaller systems. > > Has anyone stress-tested DRBD on this level of system? I think we once tested it on some 8way in the suse testlabs... > I'm concerned that even over gigabit, it simply won't be able to keep > up with the speed of writes that we get over the SCSI controllers. what (mean sustained/max) throughput do you actually have? what latency do you need? which percentage of your data base access is in fact _writes_ ? > What happens when a backlog occurs? Does the secondary machine simply > queue the changes, or can it lock up? Are there any other issues we > should be concerned about? you want to use "drbd protocol C", maybe, but really think about it and then benchmark it "B". there is no backlog. this is not rsync. from the point of view of the data base or filesystem or whatever, the write is finished when both local backend and remote backend acknowledged that this write is on stable storage. and in case you need special features, optimizations, or other support, just contact office at linbit... cheers, -- : Lars Ellenberg Tel +43-1-8178292-0 : : LINBIT Information Technologies GmbH Fax +43-1-8178292-82 : : Schoenbrunner Str. 244, A-1120 Vienna/Europe http://www.linbit.com : __ please use the "List-Reply" function of your email client.