Yeah, If plus the ability to backup the data to the BIOS/EPROM on the 
motherboard, that should be the utmost solution….

From: Andrew Gabriel [mailto:andrew.gabr...@oracle.com]
Sent: 星期一, 五月 24, 2010 18:37
To: Erik Trimble
Cc: Fred Liu; ZFS Discussions
Subject: Re: [zfs-discuss] [ZIL device brainstorm] intel x25-M G2 has ram cache?

Erik Trimble wrote:
Frankly, I'm really surprised that there's no solution, given that the *amount* 
of NVRAM needed for ZIL (or similar usage) is really quite small. a dozen GB is 
more than sufficient, and really, most systems do fine with just a couple of GB 
(3-4 or so).  Producing a small, DRAM-based device in a 3.5" HD form-factor 
with built-in battery shouldn't be hard, and I'm kinda flabberghasted nobody is 
doing it.  Well, at least in the sub-$1000 category.  I mean, it's 2 SODIMMs, a 
AAA-NiCad battery, a PCI-E->DDR2 memory controller, a PCI-E to SATA6Gbps 
controller, and that's it.

It's a bit of a wonky design. The DRAM could do something of the order 
1,000,000 IOPS, and is then throttled back to a tiny fraction of that by the 
SATA bottleneck. Disk interfaces like SATA/SAS really weren't designed for this 
type of use.

What you probably want is a motherboard which has a small area of main memory 
protected by battery, and a ramdisk driver which knows how to use it. Then 
you'd get the 1,000,000 IOPS. No idea if anyone makes such a thing.

You are correct that ZFS gets an enormous benefit from even tiny amounts if NV 
ZIL. Trouble is that no other operating systems or filesystems work this well 
with such relatively tiny amounts of NV storage, so such a hardware solution is 
very ZFS-specific.
--
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