On Fri, Feb 19, 2010 at 11:51:29PM +0100, Ragnar Sundblad wrote:
> On 19 feb 2010, at 23.40, Eugen Leitl wrote:
> > On Fri, Feb 19, 2010 at 11:17:29PM +0100, Felix Buenemann wrote:
> >> I found the Hyperdrive 5/5M, which is a half-height drive bay sata
> >> ramdisk with battery backup and auto-backup to compact flash at power
> >> failure.
> >> Promises 65,000 IOPS and thus should be great for ZIL. It's pretty
> >> reasonable priced (~230 EUR) and stacked with 4GB or 8GB DDR2-ECC should
> >> be more than sufficient.
These are the same as the acard devices we've discussed here
previously; earlier hyperdrive models were their own design. Very
interesting, and my personal favourite, but I don't know of anyone
actually reporting results yet with them as ZIL.
If you have more memory in them than is needed for ZIL, with some
partitioning you could make a small fast pool on them for swap space
and other purposes. I was originally looking at these for Postgres
WAL logfiles, before there was slog and on a different platform..
Also, if you have enough non-ECC memory there's a mode where it adds
its own redundancy for reduced space, which could allow reusing
existing kit - replace non-ecc system memory with ecc.
> > Wouldn't it be better investing these 300-350 EUR into 16 GByte or more of
> > system memory, and a cheap UPS?
> System memory can't replace a slog, since a slog is supposed to be
System memory might already be maxed out, too.
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