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? > > 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? > > Christian
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