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Full instllation much slower than live usb
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Author:  icefire [ Fri Jan 25, 2013 6:15 am ]
Post subject:  Full instllation much slower than live usb

So I am trying to revive an ols eee pc 701. I was looking for a lightweight linux distro which is suitable for old computers and stumbled upon Peppermint. I tried the live usb and was very impressed with everything - design, speed, apps.. And on top of it, there is this awesome and super helpful forum which I'm very grateful for.

After trying Peppermint Three on a love usb, I did a full installation on the usb flash drive (size: 8GB, filesystem: ext4). I created just two partitions - one for "/" and one for "/swap". However, the full installation works a real lot slower than the live usb version. And I just can't figure out why. I'm a total noob in linux so please bear with me. Maybe the reason is the ext4 filesystem? I really don't care about the lifespan of the usb drive (I've got plenty) so this is why I did a ext4 format on it. But since the journaling system is constantly reading and writing and the write speed of the usb drive is real slow, maybe this is what's causing the system to be that slow... Maybe I should try ext2? Any ideas? Thanks:)

Author:  Whit [ Thu May 02, 2013 3:23 am ]
Post subject:  Re: Full instllation much slower than live usb

Flash drives are traditionally slower than hard drives due to the materials they are made of (Metal disk vs. Semi-conductor chip) and have a maximum of 100,000 write/erase cycles on the higher end types.

"Modern flash drives have USB 2.0 connectivity. However, they do not currently use the full 480 Mbit/s (60 MB/s) which the USB 2.0 Hi-Speed specification supports because of technical limitations inherent in NAND flash. The fastest drives currently available use a dual channel controller, although they still fall considerably short of the transfer rate possible from a current generation hard disk, or the maximum high speed USB throughput.

File transfer speeds vary considerably. Speeds may be given in Mbyte per second, Mbit per second or optical drive multipliers such as "180X" (180 times 150 KiB per second). Typical fast drives claim to read at up to 30 megabytes/s (MB/s) and write at about half that speed. This is about 20 times faster than USB 1.1 "full speed" devices, which are limited to a maximum speed of 12 Mbit/s (1.5 MB/s)." quoted from http://en.wikipedia.org/wiki/USB_flash_drive for time saveing!

With this being stated I would start by asking a few questions:

1. Are you using a 2.0 USB port for maximum transfer rate, and is the OS recognizing that port as a 1.0 type? (If I remember correctly, EEE PC comes with a 2.0 USB)

2. What is your flash disk age and transfer speed? If it is older, it may have lived it's life - tasting sweet like a peppermint, but also melting into oblivion as peppermints often do. Also, the faster the drive, the quicker you tend to use up those rewrites.

Another thing to consider would be the setup of the OS. Flash drives are made of multiple fields and when you rewrite the contents of a particular memory location in a flash drive it involves copying the entire field into an off-chip buffer memory, erasing the field, modifying the data as required in the buffer, and re-writing it into the same field. This required considerable processing power and the microprocessor that is built into your flash disk is not designed to multitask. From what I understand the full OS utilizes multiple individual processes (x runs separate from y) instead of using a pyramid like system (x depends on y to run) of computing like windows so it could be overworking your flash drives microprocessor.

The programmers who prepared the live OS for flash most likely took this into consideration and allowed the programing to space out the events whereas the full OS might be written to take full advantage of the power of a hard drive.

I am only speculating, so Admins feel free to add your thoughts!

*EDIT*- Also using a partition to split your flash drive in half means you are completing the same amount of rewrites but on half the space (i assume you are using the second partition as persistence) and also writing on your other partition at the same time for memory. So here is the difference:

Live OS: The OS loads from USB, and the system uses ram to store short term memory. No long term memory. The microprocessor only has to deal with loading the OS.

Full OS on Flash: The OS loads from USB, and the system uses ram to store short term memory. USB is used for long term memory. The microprocessor now has to deal with loading the OS and long term memory thus doubling the microprocessor's workload.

Solution: It's the drive man.... just can't handle the workload. Try using an external hard drive.

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