[clug] Linux LVM or cache solutions for SSD + HDD

[Jamie Carl]

Steve,

Not 'exactly' the same as what you're asking about, but I have an SSHD
"hybrid" drive in my notebook that sort of does that stuff
automaticallyin the drive itself.

It'sa 750GB Seagate Momentus XT which has 8GB of SSD storage in it.  It
keeps the OS in the SSD, I think by access time after start-up.  The
more you boot the faster it gets until everythingyou use regularly is on
the SSD.  This approachmakes it OS independent (using mine under
Linux).  Pretty cool and fast little drive.

Interested to see if there is a way of tying multiple drives together
for larger applications as well though.

Jamie



On 25/01/13 12:10, steve jenkin wrote:
> A friend recently sent me a link about Apple "Fusion Drive".
>
>  - it's an LVM type (CS: Core Storage)
>  - concatenates, RAID-0 style, SSD & HDD drives
>    - places O/S files in SSD [not sure how it keeps them there]
>    - writes all files initially go to SSD
>    - can trigger a migration to SSD by 2 reads (copy file twice), IIRC.
> 	[fuzzy on detail, how it triggers: reads or writes?]
>  - seems to work with 128Kb blocks
>  - maintains a 4GB 'free space' on SSD
>  - Doesn't seem to need FileSystem hooks
>
> Only available on Mac Mini and iMac models, not Macbook.
>
> MSY have reasonable PC 'packages' below $1000, with extra $200 for a
> Samsung 840-series 250GB SSD. I'm tempted :-)
>
> What do Linux people use to lash SSD/HDD together?
>
>  - manual allocation + symlinks, incl nightly scripts
>  - overlay mounts of important dirs
>  - something automatic that relocates stuff
> 	(how to check HDD 'use'. atime?)
>  - bcache (?IIRC) or other SSD caching tool
>  - an LVM or 'md' config
>  - something a whole lot cooler??
>
> Thanks in Advance.
>
> cheers
> steve
>