El 13/05/14 14:23, Christian Balzer escribi?: > On Tue, 13 May 2014 12:07:12 +0200 Xabier Elkano wrote: > >> El 13/05/14 11:31, Christian Balzer escribi?: >>> Hello, >>> >>> No actual question, just some food for thought and something that later >>> generations can scour from the ML archive. >>> >>> I'm planning another Ceph storage cluster, this time a "classic" Ceph >>> design, 3 storage nodes with 8 HDDs for OSDs and 4 SSDs for OS and >>> journal. >> Christian, do yo have many clusters in production? Are there any >> advantages with many clusters vs different pools per cluster? What is >> the right way to go?, maintain a big cluster or different clusters? > Nope, I'm certainly a Ceph newb in many ways. That will be my third. > > The reasons for having different clusters can be locality (one is not at > our main DC) and also special use cases (speed vs. size vs. cost vs. > density, etc). > > Pools can do pretty much cover a lot of reasons why one would have > different clusters and I think the lower administrative overhead makes > them quite attractive. > >>> When juggling the budget for it the 12 DC3700 200GB SSDs of my first >>> draft stood out like the proverbial sore thumb, nearly 1/6th of the >>> total budget. >>> I really like those SSDs with their smooth performance and durability >>> of 1TB/day writes (over 5 years, same for all the other numbers >>> below), but wondered if that was really needed. >>> >>> This cluster is supposed to provide the storage for VMs (Vservers >>> really) that are currently on 3 DRBD cluster pairs. >>> Not particular write intensive, all of them just total about 20GB/day. >>> With 2 journals per SSD that's 5GB/day of writes, well within the Intel >>> specification of 20GB/day for their 530 drives (180GB version). >>> >>> However the uneven IOPS of the 530 and potential future changes in >>> write patterns make this 300% safety margin still to slim for my >>> liking. >>> >>> Alas a DC3500 240GB SSD will perform well enough at half the price of >>> the DC3700 and give me enough breathing room at about 80GB/day writes, >>> so this is what I will order in the end. >> Did you consider DC3700 100G with similar price? > The 3500 is already potentially slower than the actual HDDs when doing > sequential writes, the 100GB 3700 most definitely so. > > Christian. What type of disks are you going to use for OSDs? 3700 100G can handle 200MB/s in sequential writes. Is this not enought for 2 SAS disk journal? Xabier > >>> Christian >> _______________________________________________ >> ceph-users mailing list >> ceph-users at lists.ceph.com >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> >
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