Dec 202015

Taranis RAID-6 logoAnd here’s another minor update after [part 4½] of my RAID array progress log. Since I was thinking that weekly RAID verifications would be too much for an array this size (because I thought it would take too long), I set the Areca controller to scrub and error-check my disks at an interval of four weeks. Just a shame that the thing doesn’t feature a proper scheduler with a calendar and configurable starting times for this. All you can tell it is to “check it every n weeks”. In any case, the verify completed this night, running for a total of 29:07:29 (so: 29 hours) across those 12 × 6TB HGST Ultrastar disks, luckily with zero bad blocks detected. Would’ve been a bit early for unrecoverable read errors to occur anyway. ;)

So this amounts to a scrub speed just shy of 550MiB/s, which isn’t blazingly fast for this array, but it’s acceptable I think. The background process priority during this operation was set to “Low (20%)”, and there have been roughly 150GiB of I/O during the disk scrubbing. Most of that I/O was concentrated in one fast Blu-Ray demux, but some video encoders were also running, reading and writing small amounts of data all the time. I guess I can live with that result.

Ah yeah, I should also show you the missing benchmarks, but before that, here’s a more normal photograph of the final system (where “normal” means “not a nightshot”. It does NOT mean “in a proper colorspace”, cause the light sources were heavily mixed, so the colors suck once again! ;) ):

The Taranis system during daytime

The “Taranis” RAID-6 system during daytime

And here are the missing benchmarks on the finalized array in a normal state. Once again, this is an Areca ARC-1883ix-12 with 12 × HGST Ultrastar 7k6000 6TB SAS disks in RAID-6 at an aligned stripe block size of 64kiB. The controller is equipped with FBM-backed 2GiB of Reg. ECC DDR-III/1866 write-back cache, and each individual drive features 128MiB of write-through cache (I have no UPS unit for this machine, which is why the drive caches themselves aren’t configured for write-back). The controller is configured to read & discard parity data to reduce seeks and is thus tuned for maximum sequential read performance. The benchmarking software was HDTune 2.55 as well as HDTune Pro 5.00:

With those modern Ultrastars instead of the old Seagate Cheetah 15k drives, the only thing that turned out to be worse is the seeking time. Given that it’s 3.5″ 7200rpm platters vs. 2.5″ 15000rpm platters that’s only natural though. Sequential throughput is a different story though: At large enough block sizes we get more than 1GiB/s almost consistently, for both reads and writes. Again, I’d have loved to try 4k writes as well, but HDTune Pro would just crash when picking that block size, same as with the Cheetah drives. Anyhow, 4k performance is nice as well. I’d give you some ASSSD numbers, but it fails to even see the array at all.

What I’ve seen in some other reviews holds true here too though: The Ultrastars do seem to fluctuate partly when it comes to performance. We can see that for the 64kiB reads as well as the 512kiB and 1MiB writes. On average though, raw read and write performance is absolutely stellar, just like ATTO, HDTach and Everst/Aida64 tests have suggested before as well. That IBM 1.2GHz [PowerPC 476] dual core chip is truly a monster in comparison to what I’ve seen on older RAID-6 controllers.

I’ve compared this to my old 3ware 9650SE-8LPML (AMCC [PowerPC 405CR] @ 266MHz), to an Adaptec-built ICP Vortex 5085BR (Intel [XScale IOP333] @ 800MHz), both with 8 × 7200rpm SATA disks and even to a Hewlett Packard MSA2312fc SAN with 12 × 15000rpm SAS Cheetahs (AMD [Turion 64 MT-32] 1800MHz). All of them are simply blown out of the water in every way thinkable: Performance, manageability, and if I were to consider the MSA2312fc as a serious contender as well (it isn’t exactly meant as a simple local block device): Stability too. I couldn’t tell how often those freaking management controllers are crashing on that thing and have to be rebooted via SSH…

So this thing has been up for about 4 weeks now. Still looking good so far…

Summer will be interesting, with some massive heat and all. We’ll see it that’ll trigger the temperature alarms of the HDD bays…

CC BY-NC-SA 4.0 Building the 54.5TiB “Taranis” RAID-6 array and the hardware around it, part 4¾: First verify/scrub and benchmarks I forgot to post before! by The GAT at is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

  3 Responses to “Building the 54.5TiB “Taranis” RAID-6 array and the hardware around it, part 4¾: First verify/scrub and benchmarks I forgot to post before!”

  1. Hah! You have a 3.5″ diskette-label on that harddisk! (on top of the case, in that hotswap stand)
    And what does that card reader have, a floppy drive?

    Ever since I’m doing all installs with OPSI I haven’t had need for a floppy drive. Those USB floppy drives are the best. You can keep them away from all the dust, and you can read the floppy on the same drive that has written the floppy.

    • Hey Sjaak,

      Floppy labels are perfect for my backup drives, so I just use them. For most tasks that do require an FDD, I can use unlabeled floppies, so it’s ok to steal the labels. ;)

      That card reader right there is Teacs last and final combo drive model, the [FD-CR8]. It comes with a real FDD (so you have to connect it to an actual FDC, my mainboard still has one) and a “semi-modern” card reader. The card reader can still take SDHC, but no SDXC. Luckily, my camera is ok with an SDHC memory card. Previously, I had just a floppy and a crappy Hama external card reader, but I always wanted FD-CR8’s for a more clean setup, and a year ago or so I snatched two of the drives off eBay for just 1€. ;)

      But yeah, at work I’m also using a Mitsumi USB FDD that is even “XP/2000 F6 capable”, so it’s on Microsofts bootable USB floppy whitelist as well… Just more flexible.

      If I ever get a mainboard without a FDC, I might need to find a [Delock 91671] combo drive, the only one I know that connects both the card reader and the floppy drive via USB. It won’t take SDXC either though. Plus, that drive is extremely rare, and Delock doesn’t have any left either (I asked them). Well, it doesn’t look like I’m gonna buy a new mainboard or any SDXC cards any time soon anyway. :)

      • All USB FDD drives can be made to be F6 capable. Didn’t I send you those files once? I can’t remember.

        BTW, why does one of those drives have to do with only one led? (Didn’t I ask this somewhere already?)

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