speeding up disk-based laptop by moving /usr to flash?

[jay-R5TnC2l8y5lBDgjK7y7TUQ at public.gmane.org (jay-R5TnC2l8y5lBDgjK7y7TUQ at public.gmane.org)]

Couple of points on the idea, I will say I haven't researched this recently so it may be out dated with newer versions such as the newer high capacity sd cards.

1. There is a wide range of performance on the compact flash cards.  Think of these as similar to your research on the ssd drives, same idea different interface.

2. The high end cf cards, which are designed for professional dslrs, are much faster and relyable than cheaper cfs and sd cards (again not sure on the new generation of sd).  They are also designed to efficiently handle massive dumps of raw files.

3. Good compact flash cards use the same type of storage as ssd drives.  They just lack the faster interface and capacity, as well as a caching system to optimize disk use.  The same is not true of cheap compact flash or sd. 

4. I believe that cf is a more direct connection to pc card than sd cards are. Which may give another edge to cf card in performance and speed.

5. Whether or not a cf drive will give you a benefit depends a lot on usage patterns and how you can take advantage of it.  Using it as a chache or swap space will give you the best performace, but also burn out the card faster.

6. A lot of this depends on the amount of memory and your hard drive.  Max out your memory first.  And keep in mind that a new high performance spindle drive may give you the boost you want.  

7. If your current drive is a few years old, bad sectors, low spindle speeds and a small cache maybe reducing your performance.

8 I have no idea how to best take advantage of a hybrid spindle ssd configuration on a linux desktop.  But I know a lot will depend on your application usage.  As I mentioned swap/cache may be an option. Or it could be as simple as keeping a few programs and the files you use most on the cf and have then back up to the hd automatically. You will probably want to do some testing based on the apps and files you use.
 
Sent from my BlackBerry? smartphone with SprintSpeed

-----Original Message-----
From: Brendan Kidwell <brendan-j2ZBMMpYpO5eoWH0uzbU5w at public.gmane.org>
Date: Wed, 2 Dec 2009 00:19:33 
To: BLU<discuss-mNDKBlG2WHs at public.gmane.org>
Subject: speeding up disk-based laptop by moving /usr to flash?

At the last BLU meeting I was thinking out loud about buying netbook, but
I'm leaning away from that now. I think someone mentioned here "the keyboard
is just too small," and I'm starting to think the lack of 4:3 aspect ratio
netbooks is really a dealbreaker for me. I need my 768 lines.

I currently use Ubuntu 9.10 on a Thinkpad X41 Tablet.

I've thought about replacing my hard drive with an SSD device, but I'm
reading a lot of FUD that's giving me... well FUD. It seems that the cheap
SSD devices are unreliable and of unknown origin (a lot like CD and DVD
blanks) and unfortunately have a tendency to NOT report read and write
errors. Eek! Don't put your data there. And premium SSD devices are just too
expensive to justify for a home user.

So here's a possible plan I conceived tonight: My goals are to maximize the
perceived performance of my Thinkpad as well as maximizing battery life.

1. Buy a fresh battery. (No question about this step; the current one is
weak and years old.)
2. Keep the 60GB parallel ATA (IDE) hard drive and keep most of my stuff on
it.
3. Install a 16GB "133x" (20MB - 25MB per second) CF card in a PCMCIA-CF
adapter in my PCMCIA slot. -- I never use the slot for anything else.
4. Move /usr to the CF card and mount it from there with "no access time
recording" switch. Maybe also /var and /etc.
5. Maybe try putting /tmp in a RAM disk. (See what uses /tmp first and
determine if it's worth carving out the block of RAM.)

Most of the parts of the OS that don't live in /usr and /etc and /var look
like they're small enough that moving them off the disk isn't worth it, and
at this point I think I want to keep my data on the disk.

I'm guessing this will improve my boot time as well as startup time for
applications by virtual of the fact that flash memory generally has much
faster seek time than a disk.

My concerns are:

- Will keeping a CF card in a PCMCIA adapter online consume a lot of
additional power?
- Will the maximum throughput of the CF card be so slow as to overshadow the
expected reduction in seek time?

Has anyone ever tried anything like this?

Would I get different performance from using an SD card in the SD slot? From
what I read tonight it seems the "Secure Digital" interface has even more
limited bandwidth than a typical CF card.


Brendan Kidwell