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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