Lsi Megaraid 9361-81 / ST4000NM0035 or ST4000NM0025

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Taccess

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Hi

I have a Z820 PC.
I have purchased a 12Gb/s 9361-8i 2Gb LSI Megaraid Card with Cachevault .

Ok so the dilemma !

Both the ST4000NM0035 sata or ST4000NM0025 SAS have max sequential of approx 210MB/s.

The ST4000NM0035 sata is 6Gb/s
The ST4000NM0025 SAS is 12Gb/s

I am of the belief that when I connect 8 of ( either ) of these in Raid 0 it will equal 8 x read and 4-6 x write .

I know this because I have a z800 with 9285-8e and 8 x 2tb HDDs .

So back to the dilemma , basically it’s cheaper for me to buy the 6Gb/s drives so I can’t see what benefits I would get from the 12Gb/s drives

Can anyone with knowledge of this please help out, if the read and write speeds will be “ approx” the same then how will the 12Gb/s drives benifit me with the 12Gb/s LSI MegaRAID card ?
 

Taccess

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1) ST4000NM0025 :
https://www.seagate.com/www-content...se-capacity-3-5-hdd/en-us/docs/100793635b.pdf

Page 15:
128mb cache
12Gb/s
Max Sustainable Transfer Rate 2226mb/s
Maximum Internal data rate. 236mb/s
SAS Interface maximum instantaneous transfer rate 1200mb/s (dual port 2400mb/s)

2) ST4000NM0035 :
https://www.seagate.com/www-content...se-capacity-3-5-hdd/en-us/docs/100793636c.pdf

Page 7:
128mb cache
6Gb/s
Internal data transfer rate (Mb/s max 2396mb/s
Sustained data transfer rate OD. 215mb/s
I/O data-transfer rate (MB/s max) 600mb/s

3) HGST HUS726040ALA614 : https://www.hgst.com/sites/default/...7K6000_SATA_512n_OEM_Specification_Rev1.0.pdf

Page 19:
128mb cache
6Gb/s
Max Data transfer rate (Mbps). 1900mb/s
Interface transfer rate (MB/s). 600mb/s
Typ Sustained transfer rate (MB/s). 201mb/s

So I am buying 8 x 4tb hard drives. These are the 3 I have narrowed it down to and I am leaning towards the st4000nm0025 sas.

I am curious as to what the st4000nm0025 sas dual port possibilities are ? Or how if any can I use it to my advantage ?

I am curious about the relationship between the 9361-8i roc 12Gb/s controller and the st4000nm0025 sas 12Gb/s drives. Is there any advantage here maybe ?

The rest looks pretty close between the three drives.
Costs
St4000nm0025 : 6 x 4tb = 950
St4000nm0035 : 6 x 4tb = 780
HGST : 6 x 4tb = 780


Which would u buy ?
 

i386

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Dual port sas is used for HA systems with two controllers or for high performance systems (with sas ssds and not hdds though).

May I ask why you want sas drives instead of sata drives (like hgst deskstar nas or wd red)?
 

Taccess

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Two of the three drives above are sata 6Gb/s, so I am considering sata but also I have to weigh in costs and the three are available in bulk cheap with good enough specs for raid 0 array of 8.

HGST Deskstar :https://www.hgst.com/sites/default/files/resources/DS_NAS_spec.pdf
The results are identical to the specs of the HGST HUS726040ALA614 I mentioned eairlier.

WD Red NAS : WD Red 4TB NAS Hard Drive Review (WD40EFRX)
No thanks

WD Red PRO : same no thanks

Thanks for the info on the dual port, sounds nice. Shame it’s out of the equation :)

Can I ask why not SAS ? so far i believe it’s the best choice ! Is it the conectivety issue of being a sas or ...because thats what’s holding me back although I am quite confident it’s what I will get as the raid card is begging me to get them :)
 

i386

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Can I ask why not SAS ?
- SAS drives are more expensive (new, private user and not a company that gets huge discounts)
- SAS nearline drives (all hdds with 3+ tb capacity) are "normal" sata drives with a sas interface
- require a sas hba/raid controller (you can't reuse them in a normal pc when you upgrade your workstation)
 

Taccess

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What are you going to use the array for?
I am using a 960 or 950 pro for c drive and the array is going to be my DAW library Samples etc

On my current z800 my 950 pro has read 1600mb/s and write 900mb/s under PCIe 2.0. I am hoping with the Z820 which is on its way I will get full bandwidth of the 950 pro through PCIe 3.0 2500/1600 resepectively. Fingers Crossed !

Also on my z800 I have a 9285-8e with bbu and 8 x 2tb st2000dm001 which has a average data rate, read/write of 150mb/s , I have only connected 6 of them and get just shy of 6 x read and write , just under 900mb/s in raid 0.

So I am Thinking that if I don’t go with the 12Gb/s SAS drives then I may not get the full advantage of my 9361-8i card. Also latter I could do a raid 0 and compare the current 6Gb/s 64mb 2tb against the 128mb 12Gb/s 4tb and have some detailed information regarding this.

So far these are the reasons I am leaning towards the sas drives
SAS Interface maximum instantaneous transfer rate 1200mb
9361-8i controller 12Gb/s + sas drives 12Gb/s ( I hoping there’s some advantage I can learn of the test)
Durability of sas drives apparently ! Made for 24/7 thingz
 

Taccess

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- SAS drives are more expensive (new, private user and not a company that gets huge discounts)
- SAS nearline drives (all hdds with 3+ tb capacity) are "normal" sata drives with a sas interface
- require a sas hba/raid controller (you can't reuse them in a normal pc when you upgrade your workstation)
Yep those thingz bug me tooo
 

azev

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Jan 18, 2013
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i think dual port drive can also be used with mpio but you are going to need backplane with dual expanders.
 

Taccess

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i think dual port drive can also be used with mpio but you are going to need backplane with dual expanders.

Can you give help me understand the theory of this is there a drawing of the connections so I can see what your saying ?

I am thinking 9361-8i outputs to 2 single expanders and each expander outputs to 4 x sas 12Gb/s drives ? Is that right ?

Is MPIO a driver in Windows 10 or a Microsoft add on ?

Lastly what benifit would I get from this ? Does expanders create bottlenecks ?
 

i386

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MPIO = multi path input/output, one drive has mutiple paths to controller(s). It is used for high availibity (HA) systems with redundant paths from drives to host(s).
 

Taccess

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So is dual port just for 2 different devices accessing the sam sas drive or is dual port two pathways to the same pc to increase speed ?

Sorry I am not understanding what dual port does in lamens sas newbie terms
 

i386

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It can be used for both:
The Zeusram for exmaple is often used in dual port mode to increase throuput and number of iops by using two sas ports. This is done by using a special cable.
In high availability system one drive is connected to two different hbas(controllers) (through a backplane with two expanders, one expander for each port). These hbas can be in the same system(=server) or in different systems (= two servers accessing the same device)
 

Taccess

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It can be used for both:
The Zeusram for exmaple is often used in dual port mode to increase throuput and number of iops by using two sas ports. This is done by using a special cable.
So basically every dual port SAS hard drive has two ports on the sas connector. So that special cable splits a sas connector into 2 ports. WOW is that correct !

What do I need to do this please don’t tell me another 9361-8i ?

Can’t I do this with just one 9361-8i or am I limited to only 4 x SAS hard drives per 9361 ?

If this is the cable then I guess I can only use 4 x hard drives per 9361
12G Internal HD Mini-SAS SFF-8643 → (4) SFF-8680 Target-based dual port 29-pin drive receptacle - CS Electronics

Is any additional software required ? Mpio or does this just work ?

Another question is if I buy another 9361-8i and have 4 x 4tb dual port sas hard drives on each 9361-8i can I set up 1 x raid 0 in combination of the dual 9361-8i ? Is this possible

Or have I lost the plot with what your explaining ?
 

Taccess

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I think that’s the wrong special cable your taking about, it’s 11pm here in Perth I am off with the fairies. Thanks for all the info very much appreciated. Tomorrow I will google my brains out trying to understand how this works or what cable I need which will help me understand it.
 

Taccess

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Jan 21, 2018
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It can be used for both:
The Zeusram for exmaple is often used in dual port mode to increase throuput and number of iops by using two sas ports. This is done by using a special cable.)
Could u provide a link to a special cable or thread regarding this I am trying to understand the method of how I would achieve this ?
Thanks
 

Taccess

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Imgur: The magic of the Internet

After all that it was the right cable , see image link above. It clearly shows the second sas port 2 and where it is situated in the SAS backplane on the oppositee side.

That’s great news so here is a chart of the cables : http://www.molex.com/mx_upload/family/serial_attached_scsi_sff_8484/sff_tables.pdf

Here is some more info regarding the quad port sas cable known as U.2 and it’s relationship to M.2 :
http://www.molex.com/mx_upload/family/serial_attached_scsi_sff_8484/sff_tables.pdf

Here is a the dual and multilink cable differences ;
Tendencies and future possibilities of the protocol of SCSI — IT daily blog, news, magazine, technologies

The only questions remaining then are :

- Do I buy the dual port cable SFF8680 or the multilink cable SFF8639 which has the dual port + extras.
- will either of these cables fit the 3.5 inch ST4000NM0025
- what is the procedure on the windows side for this dual port cable to run properly ? Or does the dual port cable open up the extra lane and present the extra thouroughput ?

can someone please help me as I am almost there understanding this thanks
 

azev

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Jan 18, 2013
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MPIO can work on windows and linux with the proper driver installed. As far as running 2x 9361 controller in the same server I believe it would just work, the LSI raid manager software will figure it self out. For using controller in each server, HA software is needed like windows clustering for example. You can use 2 windows server accessing the same drive volume and share that.