USB root

[Psynapse]

I just bought a Bubba3. I see that there is frequent disk access by the stock Excito Arch linux image installation. I was hoping to install the Excito Arch linux to a USB flash drive (formatted as Ext4 I suppose) and then install my WD Green 2Tb and format it with XFS to use it for NAS purposes. This way, most of the time the disk heads will park (even if the platters still spin) and only unpark when I'm retrieving a file. (Overenthusiastic head parking is a problem for WD Greens.) All the OS reads and writes can be serviced by the USB flash drive.

I see that the wiki has information on a USB root but it goes on to describe using a hard disk root. It also says to obtain generic ARM Arch linux from archlinuxarm.org and later on to modify this with ReedWood's repository.

If I (try to) follow this procedure:
1) what size USB flash drive will I need and
2) will there be any practical difference, benefit or disadvantage over having used the stock Excito Arch linux image?

[Psynapse]

If anyone finds this looking for the same answers I was, Sakaki has done some amazing work on this front recently. She has produced a bootable Live USB image which is persistent and can be deployed onto the internal hard disk if desired, with no soldering(!), in the following tasteful flavours:
* Arch for B3 (3 Oct 2014 kirkwood, 3.17.1 kernel) for download requiring 4Gb flash drive;
* Gentoo for B3 (3.18.6 kernel) for download requiring 8Gb flash drive;
* Gentoo for B2 (3.18.2 kernel) for download requiring 8Gb flash drive;
and a "blinktest" tool to test compatibility of USB Mass Storage devices.

I am super grateful!

[Gordon]

You should check out THIS topic.

5 pages of hints, tips and tricks to reduce disk access. I still use the SD card method I described there for a system that is not regularly accessed for storing files or emails. You should also check the methods for setting the idle timer on the green drive to a more sane value, disregardless of what other tricks you see fit to implement.

[Psynapse]

Thanks for that thread link. It is actually the topic I myself referred to in my original post. It's just that my original link broke as the forum migrated.

You should also check the methods for setting the idle timer on the green drive

Yes definitely! Thanks. I have upped my disks' timeout to 11 minutes on the basis that some cron job or similar might touch the disk on a regular basis as every 10 minutes, so I don't want to spin the disk down seconds before that triggers every time. I have set the idle timer using my desktop:

Code: Select all

[root@compact idle3-tools]# wget http://sourceforge.net/projects/idle3-tools/files/idle3-tools-0.9.1.tgz
--2015-01-29 03:01:32--  http://sourceforge.net/projects/idle3-tools/files/idle3-tools-0.9.1.tgz
HTTP request sent, awaiting response... 200 OK
Length: 21201 (21K) [application/octet-stream]
Saving to: ‘idle3-tools-0.9.1.tgz’

100%[======================================>] 21,201      --.-K/s   in 0.1s    

2015-01-29 03:01:34 (184 KB/s) - ‘idle3-tools-0.9.1.tgz’ saved [21201/21201]
[root@compact idle3-tools]# tar xzvf idle3-tools-0.9.1.tgz 
idle3-tools-0.9.1/
idle3-tools-0.9.1/COPYING
idle3-tools-0.9.1/idle3ctl.8
idle3-tools-0.9.1/Makefile
idle3-tools-0.9.1/sgio.c
idle3-tools-0.9.1/idle3ctl.c
idle3-tools-0.9.1/sgio.h
[root@compact idle3-tools]# cd idle3-tools-0.9.1/
[root@compact idle3-tools-0.9.1]# make
[root@compact idle3-tools-0.9.1]# make install
[root@compact idle3-tools-0.9.1]# cd
[root@compact ~]# idle3ctl -V
idle3ctl v0.9.1
[root@compact ~]# idle3ctl -g /dev/sda
Idle3 timer set to 128 (0x80)
[root@compact ~]# idle3ctl -s 150 /dev/sda
Idle3 timer set to 150 (0x96)
Please power cycle your drive off and on for the new setting to be taken into account. A reboot will not be enough!
[root@compact ~]# smartctl -A /dev/sda | grep "^193"
193 Load_Cycle_Count        0x0032   199   199   000    Old_age   Always       -       5698
[root@compact ~]# idle3ctl -g /dev/sdb
Idle3 timer set to 80 (0x50)
[root@compact ~]# idle3ctl -s 150 /dev/sdb
Idle3 timer set to 150 (0x96)
Please power cycle your drive off and on for the new setting to be taken into account. A reboot will not be enough!
[root@compact ~]# smartctl -A /dev/sdb | grep "^193"
193 Load_Cycle_Count        0x0032   200   200   000    Old_age   Always       -       164

[Gordon]

Well, from THIS post you can deduct that a 1 minute idle time setting is already sufficient to keep the drive from ever parking its heads. The only way to stop that is by moving /var onto a solid state device and link /tmp to /var/tmp (it doesn't work if you mount /tmp directly on a solid state device)