Using a (small) SSD as HDD cache

purzel · 2012-04-03 18:20:30

Hi!

I've heard that in windows there is feature that lets you use a SSD in your system to boost performance. As I've heard it the System is copying the most used files onto the SSD. I'm not sure how it works but I was wondering if there is a way to do this in Linux?
I'm quite sure its not just an ordinary raid.

Since I have an unused minipcie slot and 8GB of SSD isn't very expensive...

cheers!

graysky · 2012-04-03 19:30:43

8G is plenty for your root filesystem. What not put it on there. Put /var /home /boot on your rotational disk.

purzel · 2012-04-03 20:42:35

Yes, thats possible but not efficient. There are lots of files I access regularly that reside inside home and some on root that I do not use often.

Could it really be that there is no Linux equivalent to this?

cheers!

mr.MikyMaus · 2012-04-03 21:05:52

I guess you're talking about the ReadyBoost function. It is quite useful and, at least to my knowledge, there is no such option in Linux (there are similar functionalities in both Solaris [as part of ZFS] and some flavours of BSD).

I'd recommend to do it the "old fashioned way" - divide up your data between fast ssd and slow hdd as needed. I'd go for something like this:

/ - ssd
/usr -ssd
/home - hdd
/var - hdd (due to many writes which ssd's are not very good at [yet?])
/srv - depending on the kind of your load (if you are using Arch as an actual server machine - I do )
/tmp - ram
/boot - doesn't matter

You may do some fine-tunning for your ~ subdirectories (e.g. image caches on ssd and porn on hdd) - this fine-tunning can be done by symlinking (a hell) or mount-binding (a lesser hell).

And for ssd partitions I'd definitely go for a COW-enabled filesystem (btrfs, ext*-cow, nilfs2) as it makes SSD use much faster by not rewriting data but rather do a copy-on-write (hence COW), which does not need any deleting (which is as fast as rewriting on hdd's but painfully slow on ssd's - ssd's can't do a rewrite - it can only do a delete->write).

graysky · 2012-04-03 21:08:43

How do you figure? /home is its own partition as is root. I am confused.

purzel · 2012-04-04 23:14:43

Yes! Readyboost that was the word... real shame though, preload already does the same thing with ram...

Thanks for the COW tip.

cheers!

ANOKNUSA · 2012-04-05 01:02:09

If you haven't yet spent the money on the mSATA drive, Seagate has a line of OS-agnostic hybrid drives designed for exactly what you want. They're ridiculously pricey, though.

karol · 2012-04-05 01:06:11

ANOKNUSA wrote:

If you haven't yet spent the money on the mSATA drive, Seagate has a line of OS-agnostic hybrid drives designed for exactly what you want. They're ridiculously pricey, though.

A link: http://www.anandtech.com/show/5160/seag … hdd-review

osaad · 2014-06-04 10:25:36

Take a look at Flashcache and the easier to setup EnhanceIO

Inxsible · 2014-06-04 21:31:55

osaad, do not necrobump threads. After 2 years, I highly doubt that the OP is still looking for answers.

https://wiki.archlinux.org/index.php/Fo … Bumping.22

Closing...

Arch Linux

#1 2012-04-03 18:20:30

Using a (small) SSD as HDD cache

#2 2012-04-03 19:30:43

Re: Using a (small) SSD as HDD cache

#3 2012-04-03 20:42:35

Re: Using a (small) SSD as HDD cache

#4 2012-04-03 21:05:52

Re: Using a (small) SSD as HDD cache

#5 2012-04-03 21:08:43

Re: Using a (small) SSD as HDD cache

#6 2012-04-04 23:14:43

Re: Using a (small) SSD as HDD cache

#7 2012-04-05 01:02:09

Re: Using a (small) SSD as HDD cache

#8 2012-04-05 01:06:11

Re: Using a (small) SSD as HDD cache

#9 2014-06-04 10:25:36

Re: Using a (small) SSD as HDD cache

#10 2014-06-04 21:31:55

Re: Using a (small) SSD as HDD cache

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