[OpenIndiana-discuss] Good SLOG devices?

[wessels]

I think that's the correct way to model the life expectancy.

Also factor in the economical life of IT hardware, 2 to 3 years in general.
And don't forget how quickly technology becomes obsolete these days.

I really wouldn't recommend MLC memory for a SLOG.


On Thu, Mar 3, 2011 at 12:58 AM, Ivar Janmaat <ijanmaat at xs4all.nl> wrote:
> Hello Wessel,
>
> I have some limited time right now so I thought why can't I calculate the
> wear with what I know.
>
> Kown values:
> Write IOPS per Windows VM = 5
> Number of VMs = 100
> Write blocks between 4 and 32 KB (lets assume the worst: 32)
>
> MLC: 10.000 write cycles
> SLC: 100.000 write cycles
>
> Can I do the following math?
>
> Writen: 5x100x32 = 16 MB/s
> Total amount of data which can be written to a MLC: 10.000 x 100 GB
> (capacity) = 1.000.000 GB
> Total amount of data which can be written to a SLC: 100.000 x 100 GB
> (capacity) = 10.000.000 GB
>
> Lifetime MLC: 1.000.000.000 MB / 16 MB/s = 723 Days = 2 years
> Lifetime SLC: 10.000.000.000 MB / 16 MB/s = 7230 Days = 20 years
>
> So even without testing I think the MLCs are a no go.
> I need to test if the real iops are not 10 times higher than I expect
> otherwise the SLC is also a no go.
>
> One other question:
> You said that the ZIL is only read on reboot.
> But how does the ZIL work then? How is the data transfered / synchronized
> with the real harddisk? Or is that not done at all?
>
> Kind regards,
>
> Ivar
>
>
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