On thing that would put me off the 530 is lack on power off safety (capacitor or similar). Given the job of the journal, I think an SSD that has some guarantee of write integrity is crucial - so yeah the DC3500 or DC3700 seem like the best choices. Regards Mark On 13/05/14 21:31, Christian Balzer wrote: > > 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 >
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