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Flash, Root , Raid and all that jazz....

Last response: in Linux/Free BSD
September 20, 2007 2:57:19 AM

I've been doing a bit of thinking lately about Flash drives and some possible ideas for added performance.

I had a quick dig around the net and found this little article,

Now, it uses a flash drive as an extended swap, but as a lot of people commented, it was really not noticeable, except for systems running live CD's with minimal ram and minimal swap used. Now my idea was a little different, and I've only really scratched the surface, I was looking at purchasing a few 8GB Flash drives and installing the /root partition of my linux installation onto them. My idea was to use the speed of flash to make any access to the /root partition super speedy. The theory being that using flashes exceptional read abilities, booting the system, running programs would be faster then normal HDD. From my understanding, and I could be completely wrong, but /root doesn't have a massive amount of writing, as the program is called for from HDD into ram while your working on it. So if I kept writing to a minimum, the life span of the flash drive would be improved. A periodic check of the health of the flash drives could help determine when to change the flash drives with another drive.

I was thinking about having the flash /root setup backed up daily to a partition in the back of the hard drive in case of failure. Then I started thinking about RAID.... What about setting up 2 x 8GB drives in Raid0 for even more speed? Redundancy if a drive hits its write limits? I've googled a bit and found this: Which showed some good and bad results. Looks a bit hit and miss with raid.

I'm just wondering who else out there has had similar thoughts and ideas? Anyone else have something to add to the topic? With prices of Flash drives these days, and most computers having a massive amount of USB connectors (Mine came with 12! and I built it 2 years ago...) This seems like a tasty theory of improving some of those sluggish boots and opening of programs..

Discuss :D 

More about : flash root raid jazz

September 21, 2007 5:25:37 PM

The key problem is flash, unlike RAM, burns out after xx,000 or xxx,000 write cycles which is not acceptable in most situations.

Another problem is USB was not designed with performance in mind and performs well under the 480mbps theoretical max.
September 24, 2007 6:51:17 PM

Newer flash is a lot longer living than flash of old for what I have read and observed. An IDE to compact flash adapter removes much of the USB performance penalty. Looking at the sudden rise of the SATA SDD's you know the spinning discs days are numbered, although not for a good while yet.
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September 28, 2007 3:27:02 AM

Ah, I didn't even think about SD or CF cards... If I could get some SATA -> SD or CF adaptors, that would make things a bit interesting. My Gigabyte board has 4 x SATA and 4 x SATAII plugs on it...

This might be a totally left hand idea, but I think it would be some fun to play with and see what results from it.. SD $4GB cards are around the AUD$35 mark :sol: 
September 28, 2007 11:06:58 AM

Good idea indeed and it may work rather well if you RAID enough of them together.

The key issues are the poor performance per SD Card ( about 22.5MB/sec for a 150x card according to the manufacturer, probably 11-16MB/sec for a slower $28 card )

and the limited number of writes

If you were using flash as a read only medium I believe it would be far more reliable.

A typical filesystem designed for HDDs may perform several million write cycles per day.

The Gigabyte i-RAM would offer much better performance at a higher price.

It can be RAIDed as well.

October 1, 2007 1:11:29 AM

Maybe I've made an assumption here that is biting me in the ass, but I assume that the /root partition doesn't have excessive amounts of writing going on with it. I see it as mainly a massive reading partition where it only has to write stuff when you change configs or write new bits to programs.

Probably wrong here, because I don't have much of an understanding of how an OS's kernel works at the core of things.

I like the look of the Gigabyte iRam, I was impressed with the THG review of it, but I was rather disappointed that it only supported 4GB, It would have been much more appealing if it could handle 8GB. I can get the iRam for $209, and 4GB of DDR-400 for $220. I would need two iRams to make a standard /root partition...

Ah well... anyone else got something to contribute to the idea of Flash boosting?
October 1, 2007 1:26:50 AM

I think the i-RAM2 may support 8GB.

If that is the case and if they ever produce it, maybe it would be an option.

Now if the memory cartels would stop fixing prices maybe 8+GB would be more affordable.
October 1, 2007 1:50:22 AM

Actually, on the topic of iRam, I notice it just uses a standard PCI slot, would there be any performance benefits if they went to a PCI Express X16 slot instead? A few of us happen to have SLI motherboards but don't use SLI ;-)
October 1, 2007 6:00:38 AM

In the i-RAM, the PCI slot is actually only providing power. The data is transfered over SATA and you can RAID them if you have onboard SATA RAID ( fakeRAID ) or hardware RAID.

Had they decided to go all out and made it a 16X PCI-E card then it would have been really interesting. :D