Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On 03/03/2011 12:09 PM, Florian Haas wrote: > On 2011-03-03 16:13, Digimer wrote: >> On 03/03/2011 10:05 AM, Robinson, Eric wrote: >>> I am thinking about taking a secondary node offline for maintenance >>> during production hours. I assume it cannot stay offline forever because >>> eventually the primary would run out of space to record changes that >>> need to be sync'd. Is there a way to know in advance how long it is safe >>> to stay disconnected without resync'ing? >> >> As I understand it, dirty blocks are recorded in memory. I am sure there >> is an upper limit to the counters, but I would hazard a guess that you >> would run out of RAM first. > > Gaaah, we'd never be crash safe if we recorded this in memory only. One > node fails, we track the sync, the other node fails, boom the sync > information is gone. No, DRBD is a wee bit smarter than that. :) > > You can overwrite your whole device while disconnected. DRBD will simply > eventually have flipped all the bits in the bitmap. Which it keeps on > stable storage, obviously. > > Florian Today I learned... I swear that I read that dirty blocks were kept in memory somewhere... Was this perhaps true some time in the past, or did I have a very vivid and inaccurate daydream at some point? :P -- Digimer E-Mail: digimer at alteeve.com AN!Whitepapers: http://alteeve.com Node Assassin: http://nodeassassin.org