Help w/ RAID



  • New to enterprise RAID controllers, and looking for some quick guidance.

    Working w/ an R620 10-slot w/ a Perc H710P Mini ( 1GB ), and getting ready to deploy a bunch of SSDs to it.

    Based on my recent experience w/ an R610 w/ a SAS 6/iR Integrated controller, where we found out late in the game that the controller can't/won't run the SATA SSDs at anything about 1.5 Mbps ( calls it its "negotiated speed" while listing the "3.0 Gbps capable speed" in OpenManage ) while intermingled w/ our other SAS drives, even though they're SATA III drives.

    My question is, is there a way I can tell beforehand whether the R610 will use the 6 850 Pros I bought at a lower speed or their max of 6 Gbps?


  • Service Provider

    That's a great question! I have no idea, though.

    Going to ping @xByteSean and see if he knows. Also @ryan-from-xbyte



  • H710 controllers + SSD's is a project I've wanted to do for a while, please let me know how it turns out. Better still, thrash it with some benchmarks if you have a spare hour or two!



  • @MattSpeller said:

    H710 controllers + SSD's is a project I've wanted to do for a while, please let me know how it turns out. Better still, thrash it with some benchmarks if you have a spare hour or two!

    At the moment it's going to be 6x 1TB 850 Pros in a Raid 10.

    Anyone that can answer this: Is benchmarking SSDs considered to be detrimental to longevity and long-term performance out of curiosity? Is it similar to throwing weeks of use at the hardware all at once, or nah?


  • Service Provider

    Depends, are you doing write benchmarks, then yes. Are you just doing reads, then not really.



  • @creayt those 850Pro's are rated at something like a full drive write per day for years, I'll go look it up and edit this in a few mins. TL;DR no harm done.

    Edit: 840pro received 2PB of writes, finally died. Unless you're going to benchmark it for a few months solid, you'll do nothing to their endurance.

    http://techreport.com/review/27436/the-ssd-endurance-experiment-two-freaking-petabytes/4

    Edit2: 850pro warranty: 10 years or 300TB worth of writes. That's a lot of writes.*

    http://www.samsung.com/global/business/semiconductor/minisite/SSD/global/html/support/warranty.html

    Edit3: 300TB is actually not a lot of writes on a 1TB drive, that's only ~82GB/day for 10 years.

    Edit4: the most important factor - performance over TB written to the devices:

    http://techreport.com/review/27436/the-ssd-endurance-experiment-two-freaking-petabytes/3



  • @creayt said:

    Based on my recent experience w/ an R610 w/ a SAS 6/iR Integrated controller, where we found out late in the game that the controller can't/won't run the SATA SSDs at anything about 1.5 Mbps ( calls it its "negotiated speed" while listing the "3.0 Gbps capable speed" in OpenManage ) while intermingled w/ our other SAS drives, even though they're SATA III drives.

    Pretty normal actually.

    SAS and SATA do things slightly differently. They are electrically compatible but in order to interact with each other on the same backplane they need to negotiate down to an equal speed. Sounds as though your controller only does it at SATAII on this.

    If you gank out the SAS drives, does it go at the right speed then? If you mix, does the SAS drives report and get the right speed?

    Best bet is to use another device if you want to have pure SATA SSDs. A small SAN would do the trick.

    Better question is, why didn't you get SAS SSDs?



  • @PSX_Defector said:

    SAS and SATA do things slightly differently. They are electrically compatible but in order to interact with each other on the same backplane they need to negotiate down to an equal speed. Sounds as though your controller only does it at SATAII on this.

    From reading around the net it looks like all you need is an interposer to get the full speed. Did you mean Sata I? I thought Sata II was 3 Gb, I was 1.5, and III was 6?

    If you gank out the SAS drives, does it go at the right speed then? If you mix, does the SAS drives report and get the right speed?

    Unfortunately I don't have the option of experimenting with that now. The box has some RAID going on and runs 6 or 7 mission-critical VMs.

    Best bet is to use another device if you want to have pure SATA SSDs. A small SAN would do the trick.
    Not an option unfortunately.

    Better question is, why didn't you get SAS SSDs?
    For the 840 Pros in the R610 I just had them lying around and we ended up having two flexible drive slots. For the new R620 and the 6x 1TB 850 Pros... because I presumed that they would just work, and I'm guessing SAS SSDs to rival the 850 Pros @ 1TB would be a million dollars each. If not please flip me some links, I can still return the 850 Pros. From reading around the net it sounds like some of the issue may be the mixing and matching of SAS w/ SATA SSDs in the same controller, on the R620 I'll have the datacenter techs try pure SSD before we reincorporate 4 of the leftover SAS drives into the system in case that's the difference. Was hoping there was some way to find out pre-deployment of the drives short of investing 12 hours into phone calls w/ Dell in order to find someone that's miraculously both able to speak English intelligibly and who knows what they're talking about and could actually answer my question.



  • Link to the "PowerEdge RAID Controller H710P" brochure here.

    http://www.dell.com/downloads/global/products/pvaul/en/dell-perc-h710p-spec-sheet.pdf

    1. I don't know if that's different than or the same as mine, which is a H710P Mini ( 1GB ).

    2. If it's the same, it does say that it supports "up to 32 3Gb/s and 6Gb/s SATA drives, which is a relief.



  • I can't speak for the 850's, but the SATA Edge SSD's we sell at xByte negotiate at 6Gbs and can be mixed with SAS. This works on both the H700 in the R610 and the H710 in the R620. The Edge drives will green light on the front panel but they do show up as non-Dell in open manage. While not supported by Dell, we sell these as a option to get the speed of SSD without the cost of Dell branded SSDs.



  • @todd-at-xByte said:

    I can't speak for the 850's, but the SATA Edge SSD's we sell at xByte negotiate at 6Gbs and can be mixed with SAS. This works on both the H700 in the R610 and the H710 in the R620. The Edge drives will green light on the front panel but they do show up as non-Dell in open manage. While not supported by Dell, we sell these as a option to get the speed of SSD without the cost of Dell branded SSDs.

    The R610 has a SAS 6/iR, not an H700 unfortunately.



  • Adding to what @todd-at-xByte said, our selection of Edge Drives are a great selection for either 11th or 12th gen dell servers when running the H series raid cards. Your going to be getting 6Gbps throughput on either the H700 series, or the newer H710 series cards as long as your running 6Gbps drives on the backplane. Generally i would never mix SAS and SATA on the same backplane because in my experience i have seen higher failure rates on hard drives being mixed because of the different voltages needed to run both types of drives. To answer your original question @creayt, if the 850 Pros are recognized by the backplane and raid controller, depending on the controller, they will negotiate either 3Gbps (sas 6/ir) or 6Gbps (H-series cards). This is all dependent on them even being recognized though, as they will not have the Dell enterprise firmware on them which is truly needed to be compatible.



  • @xByteSean said:

    This is all dependent on them even being recognized though, as they will not have the Dell enterprise firmware on them which is truly needed to be compatible.

    Thanks for all of the info, very handy. I read somewhere recently that Dell pushed a firmware update to the controller that took the "Dell certified" restrictions off and lets normal drives work, have you heard anything about that?



  • To anyone who'se curious: the drives ( all 6 SSDs and the 4 10k SAS HDDs ) are now deployed and all are working/"negotiated" at 6 Gbps. Hooray. The only drawback is that the SSDs are throwing the little alert symbols in open manage, though they appear to be functioning fine and at full speed. Open Manage can't read the power status, etc, and shows them as "non-critical" ( while online ). It's unfortunate.

    Pic: RAID 10 of 10ks on the left, Raid 10 of SSDs on the right.

    CLxgUIi.png



  • For fun / reference;

    840pro 256gb on AMD RAID (AHCI not passing through due to RAID enabled for another array, this is a single drive)

    upload-1302e5fb-4efa-4a1b-8e58-94d637dee590



  • @MattSpeller said:

    For fun / reference;

    840pro 256gb on AMD RAID (AHCI not passing through due to RAID enabled for another array, this is a single drive)

    upload-1302e5fb-4efa-4a1b-8e58-94d637dee590

    Now throw it into rapid mode and watch those numbers climb.



  • @creayt Can't unless it's pure AHCI 😞



  • @MattSpeller said:

    @creayt Can't unless it's pure AHCI 😞

    😞 😞 😞

    Sorry to hear that. Better luck next RAID.



  • For comparison, "cheap" sandisk 256gb SSD in my work laptop:

    upload-46cb10a5-1af4-44d0-b0d4-e02ff3e04cd1


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