FreeBSD on SSD

Waitman Gobble gobble.wa at
Mon Jul 30 15:38:12 UTC 2012

On Jul 28, 2012 11:42 AM, "Wojciech Puchar" <wojtek at>
>> The read-cache idea is very sound, mainly because by using it this way
Seagate would not have to create a special set of
>> instructions for installing and using the HDD.
> I don't think that this drive cache is smart enough to really cache
needed things and not flush that cache with useless data too often.
> i personally would prefer that drive to show up as 8GB disk and 750 GB
> It would be easy to fit most of /usr in 8GB with even large set of
software installed.
> when out of space then use softlinks and move not very used things (eg.
documentation, non-yours locales, examples, some linarly accessed big files
etc.) to disk.
>> My final question would be :
>> Seeing as the HDD only has a SATA connector, this would mean that the
SSD part already has a memory control device that regulates
>> access to that sector, whether it is a plain read-cache or not. This
would imply that FreeBSD could communicate with the HDD
>> normally, through the SATA connector, just like any regular HDD.
> indeed.
> Such a drive is a good idea, but complete lack of documentation (how it
operate) is not.
> You have to guess how this SSD-cache works because it is not documented.
> the other thing is erasing data. You want to sell that drive and clear
your data by
> dd if=/dev/zero of=/dev/disk bs=1m
> but does it clear SSD cache? i don't think so. Someone sophisticated
enough would perform raw read of cache chips and get cached data, which can
actually be the most important part (things you work on often).
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I've been using one of these drives for a few months, bought it because of
bargain price and it sounded cool.. but its true there is little
documentation, there seems to be no way to look at the SSD cache. I've read
on some ng that it takes 5 to 10 boots to "learn" which files are loaded at
boot.. maybe true. Also have not performed any comparison tests but maybe
it boots faster. ... its not like instant on though. :)

Waitman Gobble
San Jose California

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