Question 6 disk raid 10 performance help. (linux/mdadm)

Jul 20, 2020
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I am building a raid out of 6 of these: https://hdd.userbenchmark.com/SpeedTest/5792/WDC-WD2503ABYX-01WERA0

I'm using fedora 32 with mdadm and I'm trying to figure out what the best performance will be. Plus what will help with longevity of the drives. I got them for cheap for 11 dollars a peice and they might not be in the best shape.

What would be the best chunk size and should it be near/far/offset? I was hoping to get near 300m/b read/write. And if possible a full 500-600mb/s read. Would offset with max chunk size accomplish this or is near better?

Also, Is there any way to use my hardwares raid controller to enhance a software raid? It supports raid 10. Could it use a software raid to help the cpu out? I use software raid so I can transfer it between systems as needed without rebuilding and general versatility. I'm using a GA-970-D3 board. https://www.gigabyte.com/Motherboard/GA-970A-D3-rev-10-11#ov

I'm waiting for the drives to arrive in the mail atm. So, I can't do testing currently.
 

USAFRet

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Mar 16, 2013
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6x 10 year old spinning drives? RAID 10?
Why?

6x 250GB + RAID 10 = 750GB effective drive space.
6 * $11 = $66
10 year old drives = one or more is going to die soon.

Or..500GB SSD, $66. Completely crushes that for performance.
 
Jul 20, 2020
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I have an ssd. I'm using the raid drives as a workhorse so I don't kill the ssd. My boot drive is a samsung 850 pro. I'm hoping to get at least half the performance of the ssd. maybe 1:1 read so I can transfer data. Plus the drives are cheap and commonly available. Also, I don't trust SSD's with writes. I've had them fail too often.

Would a raid 10 with 6 drives be able to get 300m/b write with 300-600m/b read?
 
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anort3

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Kill the SSD? With writes you mean? Good luck with that. You killed a Samsung drive with writes? Your 850 Pro is an 850 and it uses MLC, it exceeds these 840 Evo figures. Note that real world testing doubles the official figures with these drives.

https://www.anandtech.com/show/7173/samsung-ssd-840-evo-review-120gb-250gb-500gb-750gb-1tb-models-tested/3

I have a 500GB 840 Evo I bought new in 2013. I just moved to its 4th home. An old laptop I gave my sister. I expect I'll use it again when that laptop dies. Still showing 96% health.

RAIDing a bunch of old HDDs on the other hand.....terrible idea. I don't doubt that you had an SSD die. But it wasn't due to writes. And it likely wasn't Samsung. Crappy controller failure in cheaper models maybe.
 

popatim

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Max speeds would be for large sequential files only. You'll still have all the normal lackluster response time from heads having to move and things like that

300mb/s may be possible in a raid 10
500 would only occur in a raid 0

raid 5 & 6 add write speed decreases due to parity.
 
Jul 20, 2020
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(Yea, the ssd's that died were that specific controller.)

I guess I could have gotten and M.2 and a car. I already have 2 of the drives. So, it was only 44 dollars.

I only have one pcie 1 4xpcie and 1 1xpcie card slot left in my computer and the 1xpcie might clog air for my video car. Not sure if it's good to use up at this point.

Would these have gone together:
https://www.newegg.com/samsung-970-evo-plus-250gb/p/N82E16820147741

Would this pciex16 work in a pciex16 slot at x4 speeds? Not sure if it can take the transfer rates. Let alone the board can only do 5gbs total. Not sure where the useful limit is. Is that m.2 ssd too fast for that board? Is 3.0 usable with 2.0 either compatability or speed wise? It could only go in a 1x or 16x(4xspeed) slot.

My mobo is:
https://www.gigabyte.com/Motherboard/GA-970A-D3-rev-10-11#ov

It's only pcie 2.0.

The problem is you can't get capacity with ssd for that cost. I bought this upgrade with a 2 tb drive for storage. I actually have the raid with a bunch of old drives. 2 of which are this Re4 drive. It can go to around 100gb/s max. I wanted to get it up to speed finally.

I'm also using a phenom 1100t which means the board is only running at 4000 instead of 5200m/ts. I wonder if it could use the extra or if it's limited. It would basically use the entire board bandwidth up potentially. It would be nice and fast though! 8)

Edit: just looked it up. 2.0 has only a max of 2000m/ts(with 1500 potential). It would be a waist. Although it would be good for a future computer. Although at that point something better might come along.

I might be misunderstanding M/t vs Mb. I was assuming the were the same. I can get around 32gb per second on my mobo at 4000mt? I'm not sure I'm understanding the bandwidth correctly. I havea a 1060 3gb which does around 8gb per second I think max(NVM, it's running at 8000mhz.). Not sure on the bandwith though(20%PCIE usage with guild wars 2 running.). Honestly not sure how much room I have for things over the pcie bus.

Nvidias software reports a 5gt/s pcie speed though. I'll assume it's the cpu that is limited.

I bout one of these to be my main backup drive: https://www.amazon.com/gp/product/B07H2RR55Q/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

I'm going to avoid writes as much as possible by putting everything on it and transfering to the raid for main use and have 1tb of this drive as backup and 1tb and unique storage. I'm hoping there aren't any lifespan issues with it and the cheaper price isn't because the 256 cache is from layering that makes it die faster. If so I will minimize writes. I'm actually hoping it can get decent speeds. I was looking at something for linux and ext4 and it was getting near 200-250 mb/s even though it's smr? Might have been the wrong measurement though. Maybe have been reads, but that would work for me: https://novabench.com/parts/hdd/st2000dm008-2fr102

Edit2:

BTW, my current raid 10 consists of 2 wd re4's(WD2503ABYX-01WERA0) with just under 2 years of power on time.. The other drives are 3 wd blues?(WD2500AAKS-00f0A0) with just under 5 years of power on time and 1 old seagate(ST3250310AS) with just over 8 years of power on time. All taken from the drives SMART data. I'll use the WD blues as emergency disks in case one of the Re4's decides to die until I get a replacement. 8p

I'm assuming this will get the raid up to a good working speed. It's not optimal, but its' cheap.
 
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