anybody using the gc-ramdisk?

anybody using the gc-ramdisk?

[Adam Megacz]

Has anybody tried using the GC-Ramdisk (aka iRAM -- four DDR DIMMs on a
PCI card with a battery backup)

  http://www.gigabyte.com.tw/Products/Storage/Products_Overview.aspx?ProductID=2180
  http://en.wikipedia.org/wiki/I-RAM

Performance is much better than flash memories, but the price per
gigabyte is much greater and maximum capacity is far less.  It's really
closer to the nvram cache on a hardware raid card than an SSD.  The fact
that it loses data after 16 hours without power is a little worrisome,
although it uses a standard nimh battery so you can replace that with
something that lasts a lot longer...

Anyways, I'd be interested in hearing about anybody's experience with it.

I'm thinking of using this for my md write intent bitmap and ext4
journal, with "-o data=ordered" so close() and fsync() return as soon as
the data hits the DIMMs -- no need to wait for the disk to rotate around.

Any comments?

So often I hear debates about "hardware raid" versus "software raid"
which are actually debates over whether or not you ought to have some
sort of battery-backed write cache around.

  - a

Re: anybody using the gc-ramdisk?

[Thomas Fjellstrom]

On Mon January 4 2010, Adam Megacz wrote:
> Has anybody tried using the GC-Ramdisk (aka iRAM -- four DDR DIMMs on a
> PCI card with a battery backup)
> 
>  
>  http://www.gigabyte.com.tw/Products/Storage/Products_Overview.aspx?Produ
> ctID=2180 http://en.wikipedia.org/wiki/I-RAM
> 
> Performance is much better than flash memories, but the price per
> gigabyte is much greater and maximum capacity is far less.  It's really
> closer to the nvram cache on a hardware raid card than an SSD.  The fact
> that it loses data after 16 hours without power is a little worrisome,
> although it uses a standard nimh battery so you can replace that with
> something that lasts a lot longer...
> 
> Anyways, I'd be interested in hearing about anybody's experience with it.
> 
> I'm thinking of using this for my md write intent bitmap and ext4
> journal, with "-o data=ordered" so close() and fsync() return as soon as
> the data hits the DIMMs -- no need to wait for the disk to rotate around.
> 
> Any comments?
> 
> So often I hear debates about "hardware raid" versus "software raid"
> which are actually debates over whether or not you ought to have some
> sort of battery-backed write cache around.

If I had one I might use it as a fs-cache.

>   - a
> 
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> 


-- 
Thomas Fjellstrom
tfjellstrom@shaw.ca

Re: anybody using the gc-ramdisk?

[Adam Megacz]

Thomas Fjellstrom <tfjellstrom@shaw.ca> writes:
> If I had one I might use it as a fs-cache.

I'm not sure it offers any advantage over plain old system RAM in that
capacity; I'd be just as well off putting those DIMMs on the
motherboard.

I can't use plain old system RAM for a journal or a write-intent bitmap
because system RAM is wiped out in the event of a power failure.

  - a

Re: anybody using the gc-ramdisk?

[fibre raid]

Hi Adam,

I think you will find that device pretty effective, though I'm not
sure if it will be faster than SSD in real-world scenarios or whether
you will run into other IO bottlenecks elsewhere. You can only
consider PCIe connected SSD drives like SuperTalent's and FusionIO.
though they may actually be more expensive and for your application,
you do not need a lot of space.

-T

On Mon, Jan 4, 2010 at 8:30 PM, Adam Megacz <adam@megacz.com> wrote:
>
> Thomas Fjellstrom <tfjellstrom@shaw.ca> writes:
>> If I had one I might use it as a fs-cache.
>
> I'm not sure it offers any advantage over plain old system RAM in that
> capacity; I'd be just as well off putting those DIMMs on the
> motherboard.
>
> I can't use plain old system RAM for a journal or a write-intent bitmap
> because system RAM is wiped out in the event of a power failure.
>
>  - a
>
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> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
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Re: anybody using the gc-ramdisk?

[KELEMEN Peter]

* Adam Megacz (adam@megacz.com) [20100104 21:16]:

>   http://www.gigabyte.com.tw/Products/Storage/Products_Overview.aspx?ProductID=2180
>   http://en.wikipedia.org/wiki/I-RAM
> Anyways, I'd be interested in hearing about anybody's experience with it.

I have one stuffed up to 4GB in my Photoshop rig for temp files.
Works as advertised, not a single issue in almost two years and it
knocks off the SATA bandwidth available.

However, I had issues with it in another box where the BIOS (?)
corrupted the first sector of every 512M.

My verdict: good for home use, forget it for enterprise.

HTH,
Peter