On Tue, Jul 15, 2014 at 6:18 PM, Robert Mustacchi <[email protected]> wrote:
> On 07/14/2014 08:00 PM, Nicholas Lee via smartos-discuss wrote: > > I'm building a quick Xeon E3-1246-v3 1U system (*), while waiting for the > > Haswell E5 Xeons to be out later this year. > > > > If I'm not concerned about the size of the local storage (1TB is enough) > is > > there any downside to running 4xS3500 480/600Gb SSD drives in RAID10? > > > > vs say 3x WD Caviar RE + S3500 or 730? > > The Intel S3500 while power-safe, has rather low endurance. It seems to > be designed for what seems to be a more WORM like workload (though > I semi-considered this, but I figured my write-load would be less than the specs. Over a 5 year window, the S3700 480Gb model has a massive write endurance - 4800Gb/day vs 275TB (150gb/day) for the S3500. That said 150Gb/day is still a relatively big number. I decided to double check the two kvm nodes I plan consolidate: nic@node2:/lib/modules$ uptime 22:56:17 up 557 days, 23:51, 2 users, load average: 0.04, 0.06, 0.07 nic@node2:/lib/modules$ cat /proc/uptime && cat /sys/block/sda/stat | cut -d' ' -f3,8 && cat /sys/block/sdb/stat | cut -d' ' -f3,8 48211410.68 383655491.15 37474706776 2330469635 37695182120 2330469635 2330469635*512/(48211410.68/60/60/24)/1024^3 = 2GB/day writes per disk 37695182120*512/(48211410.68/60/60/24)/1024^3 = 32GB/day reads per disk The node is doing 4GB/day writes and 37GB/day reads per disk over the last 77 days. Both those are old system running 2xE5320 with 8Gb memory. So I could fit both on those on this new system and still have lots of head room. The E3 has a memory max of 32Gb, and I plan to keep a sizable buffer and not use more than 20gb for vms. That should also balance out any demand on disk endurance. Discovered an interesting article that indicates that the endurance figures may be under reported anyway: http://techreport.com/review/26523/the-ssd-endurance-experiment-casualties-on-the-way-to-a-petabyte Other than endurance are there other issues to running pure SSD zfs pools? > obviously more writes than one). I'm not familiar with that specific WD > model, so as with most of this, it all depends on the specifics of your > workload and what your cost/performance/capacity/durability trade-offs are. > WD3000FYYZ or the smaller model, so pretty standard SATA3 enterprise drive. It's a passive direct connect backplane, so I'm not worried about SAS. This is more a the standard fallback option if SSD isn't practical. While we are talking about endurance, this was interesting as well: http://blog.backblaze.com/2014/01/21/what-hard-drive-should-i-buy/ Nicholas ------------------------------------------- smartos-discuss Archives: https://www.listbox.com/member/archive/184463/=now RSS Feed: https://www.listbox.com/member/archive/rss/184463/25769125-55cfbc00 Modify Your Subscription: https://www.listbox.com/member/?member_id=25769125&id_secret=25769125-7688e9fb Powered by Listbox: http://www.listbox.com
