Installing OS on a SSD

[toddbailey]

Hello

I'm looking for advice on using a 32 gb ssd for the system drive as a dedicated media client but also have a few general purpose questions:

Once the OS is loaded, the client is basically used to stream media content from a master fileserver.

I'd like to know do I really need a swap file since it doesn't get used very often,
Thoughts on using a ramdisk as the swap space ( I gave 4 gig memory and rarely does more than 1.5 gig every get used.

As many know ssd devices tend to wear faster in a read/write versus a read only operation, does anyone have a link that would tell me what folders are basically read only and which ones are read and write? Reason, thinking of using a 2nd hdd for read/write operations, folders that I suspect are write /var /tmp /home these are candidates for the hdd. The idea is to put writeable folders on a 2nd and keep read only to the ssd.

any other thoughts on using a ssd?

thx

[dd_wizard]

If you put swap in a tmpfs, the OS ends up swapping RAM to the tmpfs, which is in RAM. That doesn't work very well. Check out this Fedora SSD guide for some more useful information.

dd_wizard

[toddbailey]

Thanks for the link,

a lot of questions and setup to digest.. a good place to start in any event

[stevea]

Originally Posted by toddbailey

Thanks for the link,

a lot of questions and setup to digest.. a good place to start in any event

Hey Todd,

That thread needs to be cleaned up and made concise. A background project.

A linux system does not require a swap at all ! However you must understand the consequences. If your system ever runs low on memory then the kernel will pick some process and kill it. It's not necessarily the process requesting additional memory. So some process is killed seemingly at random. IOW the system starts acting erratically.

If you have a swap partition and that fills you get the same behavior.

dd-wiz' correctly describes why a ramdisk/tmpfs swap makes no sense.

Also swap is used for suspend, and you need a swap at least as large as DRAM to suspend.

So if you don't care about suspend and you are convinced of your memory usage - go for it.


=======
Short course:
You want to mount any fs on the SSD with the 'discard' option (add it to /etc/fstab entry).
There is an 'fstrim' utility that trims mounted flesystems (some of them, ext2/3/4 at least). Use it once after install.

ext2/3/4 file systems, by default-config set aside a LOT of storage for special reserved blocks to permit logs and root activity after the disk is mostly filled. The default is 5% of disk space (~1.6GB for yours) , but IMO you only need a few MB to store some logs as to why your system failed.

To recoup the 5% of reserved ext3/4 storage you need to ....
tune2fs -r 1024 /dev/sda1 # or other ext partition
You can do this on a mounted filesystem. [1024 - 4k blocks (4MB) remain as a reserve].

[dd_wizard]

I hate to contradict stevea, it's usually a good way to embarrass one's self. So I turned off swap and tried suspending before I did. Suspend seems to work fine with no swap, programs are left in memory and the machine switches to very low power mode. However hibernate writes RAM to the swap file and then performs what amounts to a shut down. So, insufficient swap will prevent hibernating your machine.

dd_wizard

[stevea]

Originally Posted by dd_wizard

I hate to contradict stevea, it's usually a good way to embarrass one's self. So I turned off swap and tried suspending before I did. Suspend seems to work fine with no swap, programs are left in memory and the machine switches to very low power mode. However hibernate writes RAM to the swap file and then performs what amounts to a shut down. So, insufficient swap will prevent hibernating your machine.

dd_wizard

Sorry - I should have said hibernate, tho the method is called 'suspend to disk'.

---------- Post added at 05:56 AM ---------- Previous post was at 05:00 AM ----------

I just updates the thread with a concise how-to in posts 67, 68, 69.

http://forums.fedoraforum.org/showth...=256068&page=5



EDIT: For a simpler reading and reference experience, those pages have been set aside as a guide and "stuck" in their own new thread. That thread is for reference only, though. Any discussions should be conducted in their own thread, or appended to an existing thread on the subject.

-- Dan

[toddbailey]

Yes a friend let me borrow a Kill a watt, so handy I purchased one and it really tells you where the energy is going, I only wish they made one for 50 amp 220 use, I'd love to monitor the stove, hot tub and water heater, but I digress.

Thank for all the great info on the ssd install.

Next Tuesday should be interesting. The power consumption of the machine isn't that great a concern, espc. when compared to the consumption of the server with all it's multi raid drives running 24x7. The major requirement is fast boot and minimal noise. The reason for a hybrid approach is to minimize disk write activity to the ssd. With thermal monitoring, I can throttle back fan speeds or replace with lower cfm/quieter devices. I used to build boxes for performance and noise and watts were not a consideration, now the roles are reversed. Being a ocassional use item in a living room environment, quick access to the desktop from power on and quiet are design goal. The hdd is a server class device and not the quietest but the cpu/gpu/case fans are louder and mask it's sound production, beside I can always utilize accoustic materials if necessary.