SAS Expander question.

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BradTheGeek

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Jun 15, 2017
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Howdy to this amazing forum. I have lurked here occaisionally, now I come to beg a question!
Apologies if it is answered, but googling and forum searching did not yeaild an answer I could parse.

The basic question is: Is there a drive size or total capacaty limit on various SAS expanders? I am looking to buy two expanders for nearly identical builds I have done and do not want to buy hardware that will not suit.

The two builds are at my house and at the IT shop I work at. Home is for media, the shop build stores drive image backups (we image nearly every machine that comes in the shop pre-service - it has saved the bacon on many occiasions).

The builds are as follows.
Dell R620 Server with Perc H810 RAID Controller. RAM and CPU vary slightly.
Both builds have an old PC case with a wired always-on PSU running 8 drives from an SFF-8088 breakout cable.
2x 1TB SATA in RAID 1 for OS duties
6x 6TB SATA in RAID 6 for storage (~24TB Total)

The current build has issues.
1. It is a little (ok a lot) ugly.
2. I have maxed out the number of drives I can conenct without an expander.
3. I have occaisionally had drives drop out of either RIAD array requiring a rebuild. SMART testing later revealed the drive good - every time. I am thinking it may be power issues, but not sure.

I want to go ahead and get the drives in both systems moved to Norco cases with a SAS expander. This will allow for further growth, and the attachment of hot spares (and hopefully resolve any power issues I may have).

That brings me back to the first question. What SAS expander should I use to ensure I do not hit any capacity limits or have other headroom issues.

If you see any other potential areas of problem or improvement let me know!

Thanks in advance!
 

i386

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Mar 18, 2016
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Get sas2 (6bps) or newer expanders, the first generation had issued with sata drives over 2tb. I would look for intel or hp branded expanders.

Personally I wouldn't use norco chassis: they used to have problems with different components (eg backplanes frying the connected drives) and from what I read here (and other forums) their support is bad...
 
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BradTheGeek

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Jun 15, 2017
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Get sas2 (6bps) or newer expanders, the first generation had issued with sata drives over 2tb. I would look for intel or hp branded expanders.

Personally I wouldn't use norco chassis: they used to have problems with different components (eg backplanes frying the connected drives) and from what I read here (and other forums) their support is bad...

That is great info. I am looking for inexpensive but quality. What chassis would be a better choice?
 

_alex

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Jan 28, 2016
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i'd go for supermicro sc826 with bpn-sas2-826el1 that has the Expander on the backplane.
Not cheapest but can often be found at ebay for reasonable price.
 

BradTheGeek

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Looks a little out of range. I found a cheap one on ebay with a different backplane that is advertised as SAS2, but I think that is an error (or outright fabrication). A little googling shows that it is prefixed SAS and may not be good enough.

I am thinking this:
http://www.rosewill.com/rosewill-rs...-hot-swap-drives-5-cooling-fans-included.html

I have read a couple builds where I should be able to take a case like this, a good PSU, and a mobo with no cpu. This Mobo should power the SAS expander. Then cable the server to the expander and the expander to the drive bays.

Sound like a sane plan?
 
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Aestr

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Oct 22, 2014
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What's your budget per chassis? Looking at the Rosewill case you put up you're already in the price range of a nice used SAS2 Supermicro case on eBay. Add to that the price of a PSU, mobo, expander and you're paying more money for less quality. I'm away from my desk, but if someone doesn't beat me to it I'll throw in some links later today.


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BradTheGeek

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Well I just read through some other posts, including the SAS expander Wiki (dont know how I did not find that earlier). I think I may have most of my questions answered!
 

_alex

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Backplanes in sm chassis can be changed in ca. 10 minutes, bpn-sas2-826el1 currently for usd 60 at ebay, sometimes even for less.
 

BradTheGeek

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What's your budget per chassis? Looking at the Rosewill case you put up you're already in the price range of a nice used SAS2 Supermicro case on eBay. Add to that the price of a PSU, mobo, expander and you're paying more money for less quality. I'm away from my desk, but if someone doesn't beat me to it I'll throw in some links later today.


Sent from my iPhone using Tapatalk

Since I work in an IT shop and have tons of parts laying around, PSU and mobo add up to zero. Same for most cables.

Every supermicro I was looking at was $800+ except one on ebay that looked to have a SAS1 backplane. A replacement backplane/expander was $200-400. So I was looking at a minimum of 300-500 for a supermicro, used that may not have been fully usable. Likely a lot more.

With the Rosewill, the chassis, rails, and a decent expander totaled $365. All new. I know Rosewill is lower quality, but I have used other Rosewill PC cases and parts, and they do tend to work.

I am interested in the links, but I was aiming for sub $600 and it looks like rosewill is in that range, new, and better understood by me.
 

_alex

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Jan 28, 2016
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I bought two 826 with sas2 expander and dual psu for sub 400 each last year. With a bit patience this should still be possible, and you get high quality, very flexible chassis with no need for an additional (expensive) expander.
 

CyberSkulls

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Apr 14, 2016
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Since I work in an IT shop and have tons of parts laying around, PSU and mobo add up to zero. Same for most cables.

Every supermicro I was looking at was $800+ except one on ebay that looked to have a SAS1 backplane. A replacement backplane/expander was $200-400. So I was looking at a minimum of 300-500 for a supermicro, used that may not have been fully usable. Likely a lot more.

With the Rosewill, the chassis, rails, and a decent expander totaled $365. All new. I know Rosewill is lower quality, but I have used other Rosewill PC cases and parts, and they do tend to work.

I am interested in the links, but I was aiming for sub $600 and it looks like rosewill is in that range, new, and better understood by me.
I may be way off base here but it sounds like you were looking at the 24 bay SM chassis with SAS2 backplane if they were showing up that high. Since the Rosewill will hold 12 drives the SM equivalent to look at is the 826. It will be nowhere near $800. They used to run sub $300 on eBay with the SAS2 backplane.


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Aestr

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Oct 22, 2014
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Agreed with @CyberSkulls that it looks like you're not comparing equivalent items.

SUPERMICRO 2U JBOD CSE-826 CSE-PTJBOD-CB2 BPN-SAS2-826EL2 2 X PWS-1K21P-1R 12BAY | eBay

That's a quick example I found. Quite likely there are cheaper options since that's actually a dual ported backplane, which you don't need. That includes a JBOD power controller, so there is nothing else you need to buy except rails.

If you want to go with the Rosewill that's totally fine, but I think the Supermicro route is in the same price range and you'll be glad you did in the long run. Once you have it in hand the Supermicro solution is actually easier to configure and manage and for a JBOD there's really nothing new for you to learn.
 

Tom5051

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Jan 18, 2017
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Your drives keep falling out of RAID because you are most likely using cheap consumer drives that don't support the lower timeout values used by hardware RAID. Google TLR for more details about that as I don't feel like typing out an explanation.
 

BradTheGeek

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Thanks all. I think I am going to get one of each and do my own comparison.

Tom5051, its TLER and I am aware of it. The main storage array is using WD Reds, so that is fine. the OS array random 1TB drives. I would be inclined to agree with your assessment if it was just the OS array degrading, but the storage array has as well. On both builds.
 

Pri

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Jul 30, 2014
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Having used expander cards for a long time (many years) I would recommend you to purchase a case that has a SAS Expander built into its drive backplane.

Not only does it result in a much neater inside (only 1 to 2 cables need be used) but it also reduces costs for the extra cables you'll need and relieve you of a PCIe slot that you'll need to power most of the expander cards.

This is the only thing I wanted to say regarding the expander thing. If you get a Gen 2 or 3 you'll be fine with large disks. Newer cases usually offer generation 3 expanders powered by LSI and those are excellent.

Good luck :)