April 30, 20188 yr On 3/18/2018 at 2:40 PM, johnnie.black said: Not with SATA3 drives, only if you use SAS3 drives. This used to be the case, some of the new SAS3 Expanders from Broadcom (LSI) support DataBolt bandwidth optimizer technology enabling full bandwith even when 6Gbit SATA drives are used.
May 3, 20188 yr You will need SAS disks or SSD to make use of 12gbit backplane. The 6gbit controller maxes out at 500mbyte a second, this can be seen when SSD that are faster than 6gbit controller max out at 500-520mbyte read/write. The sata3 disks max out at 220mbyte per second although realistic is more like 120-180mbyte a second. Which is why they made m.2 slots and used the pci-e slot. I would like to have only m.2 nvme NAS and 10gbit networking. It would be gigabit per second transfer speed. Wait 10 years maybe then. Edited May 3, 20188 yr by Simontv
May 4, 20188 yr On 3/22/2018 at 9:14 AM, MvL said: If the times come when ssd's of 50TB are affordable what speed do we get with these ssd's? Because ssd's are faster as hdd's. I assume that the sata interface is also the limit. So that should be again 4x600MB/s = 2400MB/s (theoretical). 80-100MB/s single link. That's a pity cause the ssd's are a lot faster. I'm not sure if a expander chassis is a good idea... What workload are you expecting to require such bandwidth, and thus invalidate using the expander chassis?
March 11, 20197 yr Hello everyone! So sorry for posting on an old thread, but it's as close to my issue as I can find. I'm new to Unraid and I've been planning my NAS build for some time. I'm planning to use the GA-7PESH2 mobo with onboard LSI SAS2008 alongside the HP expander. I was planning to dual channel it into the mobo and connect most of my HDDs to the expander.... Then I read that the expander will only negotiate to SATA II speeds at 3GB/s even if the drives are SATA III capable. Should this be cause for concern? I’m planning to use 12 10TB 7200rpm WD Red drives over SATA for my data array and 2 1TB SSDs as my cache array. The cache array will be directly connected to my MOBO over SATA III to ensure the fastest transfer rates possible. Should I be worried about transfer rates if most/all of my data drives are only connecting at 3GB/s? I did check https://forums.unraid.net/topic/41340-satasas-controllers-tested-real-world-max-throughput-during-parity-check/ but there wasn’t much help there. And I’ve been reading though this thread here trying to verify my access speeds, but I’m not quite understanding the math. Let me also mention that I'm planning to link this to my main server over a 10GbE link so I can stream 4k content off of it. Which is why the speed is of such great concern to me. Can any one assist? Edited March 11, 20197 yr by DeathByDentures Additional detail added for clarification.
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