Flash disk vs hard disk?

az · February 17th, 2008

Originally Posted by fwendt

Interesting. While changing jobs, I got a new laptop and tired of the bad battery performance with the old laptop I decided I had enough money to buy a SSD to get more time programming before running out of power. This hasn't really been that much of a great buy yet.
dmesg says it's a
scsi 2:0:0:0: Direct-Access ATA TS32GSSD25S-M 2007 PQ: 0 ANSI: 5
a Transcend 32 GB (slow) 2,5" SATA SSD MLC and as I've had no real time playing with it I just asked gparted to shrink and move partitions/filesystems from the disk that came with the laptop (Thinkpad T61).

Basically, I don't know what filesystem to use to get the best possible performance out of this SSD. If you have any theories I'd be glad to hear them and hopefully test them out.

Thanks in advance, Fredrik

The OLPC XO uses JFFS2. You can install mtd-tools and create a JFFS2 filesystem using Ubuntu.
http://packages.ubuntu.com/gutsy/utils/mtd-tools

However, I think your device is built to emulate a block device. I think that jffs2 is meant for hardware that accesses the NAND memory directly. But I'm not sure.

**Sunnz** · February 17th, 2008

Originally Posted by gn2

If it's for connecting other computers to for internet access, why not just use a router?

It will be cheaper and greener.

Can't find a router that does what I want. There are expensive Cisco one, but they cost way more than my old computer.

**BlueKoala** · February 19th, 2008

Just for the sake of comparing:

Here's the results for a SATA2 750gBs WD HDD

sudo hdparm -tT /dev/sda

/dev/sda:
Timing cached reads: 1652 MB in 2.00 seconds = 825.88 MB/sec
Timing buffered disk reads: 282 MB in 3.02 seconds = 93.46 MB/sec

Just imagine having 2 of these hot rods in RAID 0

That would be rocking

But yeah, I suppose you can't go wrong with a 10$ USB thumb drive =]

**Sunnz** · February 21st, 2008

Ok I tested the boot speed between a SATA2 Raptor at 10'000 RPM and a Flash USB2.0 thumb drive.

The result was... they had exactly the same boot up time!

They were both just running a default installation of OpenBSD, it is very minimal!!

Decisions decisions... should I use the USB as additional SWAP or?

**BlueKoala** · February 21st, 2008

Someone had corrected me earlier on my statement that flash is probably not recommended as swap. It will probably take years for the flash memory to wear out. Although, USB thumbdrives are really cheap and to setup a machine as a router/gateway probably won't take as much disk space as a 10 000rpm drive would offer. I would personally opt for USB and see how it goes. If it explodes one day then I have the comfort of knowing it was a just a USB drive =]

**schmolch** · February 28th, 2008

Fredrik,

you made one big mistake with that SSD you got.
Transcend sells 2 kind of SSDs:

8, 16GB with SLC chips
32GB with MLC (soon SLC as well) chips

The MLC Chips are VERY VERY slow, that's why their 32GB SSD costs ten times less than other SSDs that size.
If you look up the specs at transcend's site the MLC SSD has about 8MB/s write and 3MB/s random write speed.

Return it if you can!

The SLCs on the other side are much better, im using the 8GB SLC SSD and i like it very much. While it has only a modest 28MB/s r/w (8MB/s random write) the ultra-fast access times make a big difference in desktop usage. Alot of delays you usually get are just gone now, like when using the menu, switching between apps, launching apps etc.

**mips** · February 28th, 2008

Originally Posted by Sunnz

Can't find a router that does what I want. There are expensive Cisco one, but they cost way more than my old computer.

You could always build your own. OpenBSD would be nice for such a project.

If you want to use flash I would advise Compact Flash via a IDE adapter. This way the compact flash is actually seen as a regular ide drive.

**fwendt** · February 28th, 2008

Originally Posted by schmolch

The MLC Chips are VERY VERY slow, that's why their 32GB SSD costs ten times less than other SSDs that size. [...] Alot of delays you usually get are just gone now, like when using the menu, switching between apps, launching apps etc.

Yes. I took a chance and I only got 2/4 of what I was hoping for.
+ less power consumption
+ silent operation
- really fast reads -> no big difference from the other drive
- ok writes -> major slow down

It's too late to return the disk and I've almost gotten used to the delays that sometimes occur. Mounting the filesystem (which is ext3) with noatime made the difference between barely usable and acceptable.

8 GB is just too small to really be usable imho.

Thanks anyway.

**Sunnz** · March 1st, 2008

Originally Posted by mips

You could always build your own. OpenBSD would be nice for such a project.

Yea that's exactly why I started this thread.

If you want to use flash I would advise Compact Flash via a IDE adapter. This way the compact flash is actually seen as a regular ide drive.

Hmmm didn't know that they existed!

Well I have already pulled on a Flash drive out of a MP3 player that I don't use anymore, plugged in back into the USB port of the back of my computer, and it is up and running now!