5

I'm just curious if it is possible do it. I have a spare 4gb sd card.

user128712
  • 2,372

2 Answers2

3

Because the bandwith of the SD card interface is quite low compared to even a regular HDD (around 20Mb/s compared to 70-100Mb/s) it will be much slower. Where you can gain speed is by adding as much RAM as possible, and using an SSD instead of the HDD.

Frantique
  • 8,493
  • What SD-cards are you refering to? If I would do this I would pick an Ultra fast at 100MB/s read and 90MB/s write. – Alvar May 31 '13 at 14:10
  • Like this one, http://www.sandisk.com/products/memory-cards/sd/extremepro-sdxc-sdhc-uhs-1-95mbs/?capacity=8GB – Alvar May 31 '13 at 14:13
  • 2
    The r/w speed of your SD card will always depend on your card reader interface. I've just gave you an example for a regular one, but as you can see even an ultra fast card it is just around a slow HDD. A newer SATA HDD will have something like this: Timing cached reads: 23910 MB in 2.00 seconds = 11973.87 MB/sec Timing buffered disk reads: 360 MB in 3.05 seconds = 118.09 MB/sec – Frantique May 31 '13 at 14:13
  • I just looked up my HDD and it read/writes at 130MB/s, so never mind. – Alvar May 31 '13 at 14:17
  • Ok, give a try. Also consider that an SD card's cells writing lifetime is really low for an OS, so you have to force to RAM as much you can. – Frantique May 31 '13 at 14:21
  • 1
    130MB/s is quite good but keep in mind that the further the read heads move, the lower the speed becomes. It is possible for hdd to lose up to 40% of maximum speed (depending on make and model). Also, another alternative to SSD is a fast USB3 stick. – hmayag May 31 '13 at 14:23
  • I too have tried this... not gonna work like you think. I have an older laptop sitting around with a pata 60GB drive and the sd was WAY slower. Mabey it might help as a swap drive since you will be using 2 drives, but I haven't tested it. – Scott Goodgame May 31 '13 at 15:58
  • By any chances, is it also good or recommendable to make it as an additional swap. – user128712 Jun 01 '13 at 08:53
0

The question is about using an SD card to store frequently accessed files caching these in de SD card instead of the pagefile... That's Windows stuff in fact. Windows uses a special algorythm amd compression to do that. However: Even in our "beloved" MS operating system ReadyBoost does only provide a very limited improvement on realtively up to date hardware and it is more a way to speed up older drives.

I know that your question is not about MS Windoze, but before giving an answer for Linux I had to exaplain what the hype is all about.

Linux does not work like Windows (and neither Mac OS X for that matter) and the key here is memory management. All this readyboost stuff just isn't applicable and it doesn't make much sense. In Linux the closest thing would be using the SD card as extra swap... you can find it here in Lifechaker

BUT before doing that I would encourage you to read the comments.

So, maybe your 4GB SD card may be better employed for other stuff such as putting a little virtual machine into it or holding a small read-only rescue system.

BTW: In Raspberry Pies this stuff seems to make actual sense ;)

runlevel0
  • 343
  • 1
  • 7
  • 16