[mdlug] SSD - flashcache or bcache

[Michael ORourke]

-----Original Message-----
>From: Aaron Kulkis <akulkis00 at gmail.com>
>Sent: Jan 13, 2014 10:56 PM
>To: MDLUG's Main discussion list <mdlug at mdlug.org>
>Subject: Re: [mdlug] SSD - flashcache or bcache
>
>Michael ORourke wrote:
>> Lug Nuts,
>>
>> Anyone out there using either of these technologies, flashcache or bcache?  Basically looking to add some speed to a filesystem, but would like to keep the existing RAID 1 volumes for redundancy.
>>
>> -Mike
>
>As I understand it, Compared to disks, when writing, the throughput to flash memory is slow.
>
>Flash memory is GREAT for things like directories like /etc, /bin, /sbin, /usr/bin, /usr/sbin,
>because the files in them are written VERY occasionally (software updates and configuration changes),
>and so there are al the advantages of a technology that eliminates the disk-drive associate
>delays of read/write head seek time and rotational delay.
>
>Also, using flash for swap space is just going to wear out very expensive memory very quickly.
>
Aaron, I am going to disagree with you on this one.  Are we talking about the same technology?
I was referring to: https://wiki.archlinux.org/index.php/flashcache
Which sounds like a reasonable way to speed up IO in a server on a limited budget.
The other thing... it seems like it would be difficult, administration-wise, to have a handful of directories living on the SSD.  Probably a lot easier to just dump root onto the faster drive and map say /home to a slower device.  Just my 2 cents worth.
-Mike