On 27-4-2017 20:46, Alexandre DERUMIER wrote: > Hi, > >>> What I'm trying to get from the list is /why/ the "enterprise" drives >>> are important. Performance? Reliability? Something else? > > performance, for sure (for SYNC write, https://www.sebastien-han.fr/blog/2014/10/10/ceph-how-to-test-if-your-ssd-is-suitable-as-a-journal-device/) > > Reliabity : yes, enteprise drive have supercapacitor in case of powerfailure, and endurance (1 DWPD for 3520, 3 DWPD for 3610) > > >>> Also, 4 x Intel DC S3520 costs as much as 1 x Intel DC S3610. Obviously >>> the single drive leaves more bays free for OSD disks, but is there any >>> other reason a single S3610 is preferable to 4 S3520s? Wouldn't 4xS3520s >>> mean: > > where do you see this price difference ? > > for me , S3520 are around 25-30% cheaper than S3610 I just checked for the DCS3520 on https://ark.intel.com/nl/products/93005/Intel-SSD-DC-S3520-Series-1_6TB-2_5in-SATA-6Gbs-3D1-MLC And is has a TBW of 2925 (Terrabytes Write over life time) = 2,9 PB the warranty is 5 years. Now if I do the math: 2925 * 104 /5 /365 /24 /60 = 1,14 Gbyte/min to be written. which is approx 20Mbyte /sec or approx 10Gbit/min = 0,15 Gbit/sec And that is only 20% of the capacity of that SATA link. Also writing 20Mbyte/sec sustained is not really that hard for modern systems. Now a 400Gb 3710 takes 8.3 PB, which is ruffly 3 times as much. so it will last 3 times longer. Checking Amazone, I get $520 for the DC S3710-400G $300 for the DC S3520-480G So that is less than a factor of 2 for using the S3710's and a 3 times longer lifetime. To be exact (8.3/520) / (2,9/300) = 1.65 more bang for your buck. But still do not expect your SSDs to last very long if the write rate is much over that 20Mbyte/sec --WjW _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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