Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Hi Adam, I'm sorry but it wasn't supposed to be an off-topic. I have been checking all the phases of this process, and RAID is something I was checking as well. What I wanted to know was really the DRBD side, as I know that this expansion will affect the block numbers and so on. That is why I wanted to know if DRBD would handle it okay, and how! Thanks ALL, for the messages! I will check the version numbers and publish the results here. And I will RTM. Thanks again, --Marcelo On 1/31/13 12:27 PM, "Adam Goryachev" <mailinglists at websitemanagers.com.au> wrote: >On 01/02/13 04:04, Justin Edmands wrote: >> I'm on the fence about the amount of time it will take to degrade and >> rebuild a RAID6 at 16 drives (x2 systems). >> >> Anyone against the idea of: >> Backup data friday night through saturday morning >> stop drbd and heartbeat on node2 >> replace all drives on node2 >> build raid 6 and match setup/sizes from node1 >> initialize metadata, etc. >> start drbd and heartbeat >> let it sync >> make node2 primary >> repeat steps for node1 > >In theory, the set of drives you pulled from the secondary are an extra >backup.... you could put all those drives back in, and make that set the >primary.... In some ways this might be a better solution, since you are >then simply doing a single large read on the primary, and a large write >on the secondary.... no raid rebuilds, except for the initial resync on >the secondary (which you might be able to skip since you know you will >write to every sector very soon when drbd does the sync). > >1) Stop DRBD on secondary >2) Pull all drives on secondary >3) Add all drives on secondary and build new RAID6 array >4) Enable DRBD on secondary >5) sync from primary to secondary > >Danger of read errors on the primary during this sync, but I would guess >this is better than doing 16 rebuild's > >Personally, I would try to set the primary read-only during the process >(if an option) so that the "spare" set of drives is an exact match to >the primary (ie, they don't get outdated). > >Depends on how much downtime can be scheduled.... > >Finally, I think you have a fairly high risk with 16 drives in a single >RAID6, you might consider 2 sets of 8 drives in RAID6, and do a linear >concat of the two sets (or raid0). That allows you to lose any 2 out of >8 drives, instead of only 2 out of 16. Also, chances of URE on just one >of the remaining 14 drives after a 2 drive failure is not a good risk I >would want. Though depends on capacity requirements if you can use >another 2 drives to ensure you don't lose the data. > >Just my 0.02c worth.... > >At the end of the day, the direct answer to the original question was >RTFM, it really is a very nice manual, and you didn't tell us what >version of DRBD you use. The rest is really off-topic for this list, >maybe discuss on the linux-raid list if you are interested. > >Regards, >Adam > >> On Thu, Jan 31, 2013 at 11:20 AM, Adam Goryachev >> <mailinglists at websitemanagers.com.au >> <mailto:mailinglists at websitemanagers.com.au>> wrote: >> >> On 01/02/13 02:58, Marcelo Pereira wrote: >>> Hello Everyone, >>> >>> I'm about to perform an upgrade on my servers and I was wondering >>> how to do that. >>> >>> Here is the scenario: >>> >>> Server A has 16x 1Tb hard drives, under RAID-6. >>> Server B has 16x 1Tb hard drives, under RAID-6. >>> >>> And both are in sync, using DRBD. >>> >>> I though about replacing the hard drives for 2Tb units, one by one. >>> >>> So, on each run, I would: >>> >>> * Remove a 1Tb disk >>> * Add a 2Tb disk >>> * Wait for it to rebuild the RAID >>> >>> After replacing ALL disks, I would expand the RAID unit, on each >>> server. >>> >>> However, I was wondering how DRBD would "like" this procedure. >>> >>> I know that, before "expanding" the RAID, the cluster size, and >>> the block numbers would remain the same, as I would be "wasting" >>> the extra space on the newly added drives. >>> >>> So, after "both" servers have all the drives replaces, and the >>> RAID is properly rebuild. Would that be a problem to expand it? >>> How would DRBD handle it? >>> >>> I will appreciate any comment or suggestion here. >> DRBD will work perfectly... >> >> You probably need to do the following: >> 1) Pull one drive and replace (you could do one on each server at >> the same time, although better/safer to do one server at a time) >> 2) Wait for rebuild to complete >> 3) Repeat for all disks on BOTH servers >> 4) Resize the RAID array on each server >> 5) Resize DRBD (see the fantastic online manual for your version of >> DRBD for the details) >> 6) Resize the underlying filesystem or whatever >> >> BTW, depending on your kernel version, and/or RAID (I'm assuming >> linux software raid), you might like to query the linux-raid list to >> see if you can ADD the new drive, tell md that this new drive is >> replacing drive X, this way you avoid degrading the RAID array, >> hence lose less performance during the rebuild, and have a lower >> risk of disk failure and especially URE (Unrecoverable Read Error) >> during the rebuilds. >> >> Regards, >> Adam >> >> >> -- >> Adam Goryachev >> Website Managers >> www.websitemanagers.com.au <http://www.websitemanagers.com.au> >> >> >> _______________________________________________ >> drbd-user mailing list >> drbd-user at lists.linbit.com <mailto:drbd-user at lists.linbit.com> >> http://lists.linbit.com/mailman/listinfo/drbd-user >> >> > > >-- >Adam Goryachev >Website Managers >www.websitemanagers.com.au >_______________________________________________ >drbd-user mailing list >drbd-user at lists.linbit.com >http://lists.linbit.com/mailman/listinfo/drbd-user