Spanning OSDs over two drives
Hi all I have a scenario where I'm upgrading to ceph octopus on hardware that groups its drives in trays which contain 2 devices each. Previously these drives were joined in a software RAID1 and the md devices were used as the OSDs. The logic behind this is that should one of those drives fail, both will need to be removed at the same time due to the design of the machine. For example: https://www.servethehome.com/supermicro-ssg-6047r-e1r72l-72x-35-drive-4u-sto... As I understand that using RAID isn't recommended, how would I best deploy my cluster so it's smart enough to group drives according to the trays that they're in? Thanks!
On 9/18/20 8:53 AM, Liam MacKenzie wrote:
I have a scenario where I'm upgrading to ceph octopus on hardware that groups its drives in trays which contain 2 devices each. Previously these drives were joined in a software RAID1 and the md devices were used as the OSDs. The logic behind this is that should one of those drives fail, both will need to be removed at the same time due to the design of the machine.
For example: https://www.servethehome.com/supermicro-ssg-6047r-e1r72l-72x-35-drive-4u-sto...
As I understand that using RAID isn't recommended, how would I best deploy my cluster so it's smart enough to group drives according to the trays that they're in?
Just as usual - one drive is one osd. When your failure domain is "host" or "rack" just stop both of osd daemons and do maintenance. k
Hi, Am 18.09.20 um 03:53 schrieb Liam MacKenzie:
As I understand that using RAID isn't recommended, how would I best deploy my cluster so it's smart enough to group drives according to the trays that they're in?
You could treat both disks as one and do a RAID0 over them with one OSD on it. Double the space and the same risk. If you have at least "host" as failure domain then you even have no copies of the same object in one single host. That means it does not matter if you take two OSDs offline at the same time. Regards -- Robert Sander Heinlein Support GmbH Schwedter Str. 8/9b, 10119 Berlin http://www.heinlein-support.de Tel: 030 / 405051-43 Fax: 030 / 405051-19 Zwangsangaben lt. §35a GmbHG: HRB 93818 B / Amtsgericht Berlin-Charlottenburg, Geschäftsführer: Peer Heinlein -- Sitz: Berlin
participants (3)
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Konstantin Shalygin
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Liam MacKenzie
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Robert Sander