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. 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. Christian -- Christian Balzer Network/Systems Engineer chibi at gol.com Global OnLine Japan/Fusion Communications http://www.gol.com/
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