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 > non-volatile. System memory might already be maxed out, too. -- Dan.
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