Pupsave on USB when using separate data partition

[ETP]

greengeek wrote:

There seems to be a huge variation in write speed between brands/models. Without an LED it's guesswork. Might have to stay away from micro-SDs.

Here are some rough & ready stats on read speeeds. As a rule of thumb write speeds are generally
less than half the read speed.
Whilst these do not effect USB/SD live running they impact boot up speed and save time.

sh-4.1# hdparm -t /dev/sdb1 (USB2 STICK - FAT32 PARTITION)
/dev/sdb1:
Timing buffered disk reads: 26 MB in 3.78 seconds = 7036 kB/s
sh-4.1# hdparm -t /dev/sdb2
-------------------------------------------------------------------
/dev/sdb2: (SAME USB2 STICK - EXT4 PARTITION)
Timing buffered disk reads: 63 MB in 3.04 seconds = 21194 kB/s
sh-4.1# hdparm -t /dev/sda1
-------------------------------------------------------------------
/dev/sda1: (NTFS HDD - WD 7200rpm SATA-2)
Timing buffered disk reads: 146 MB in 3.00 seconds = 49717 kB/s
sh-4.1#
-------------------------------------------------------------------
sh-4.1# hdparm -t /dev/sde1 (16MEG FAT32 SmartmediaCard)
/dev/sde1:
Timing buffered disk reads: 13 MB in 3.01 seconds = 4412 kB/s
sh-4.1#
-------------------------------------------------------------------

Given the (not surprising) speed advantage and robustness of EXT4 it actually makes sense to
place both the main sfs & the save file on that 2nd partition but keep initrd and
vmlinuz on the fat32 boot partition. I have been running such a config on one of
my sticks for some time. The boot codes were tricky to get right but are as follows:

Code: Select all

LABEL 5332
MENU LABEL Slacko 5.3.3.2    05/07/12
KERNEL /p5332/vmlinuz
APPEND initrd=/p5332/initrd.gz pmedia=usbflash pupsfs=sdb2:/p5332/puppy_slacko_5.3.3.2.sfs psavemark=2

That and the figures for the HDD lead onto my placing the main sfs & save file on the hard drive
but booting from SmartMedia......but thats another story!

[greengeek]

Whilst these do not effect USB/SD live running they impact boot up speed and save time.

I find that if I allow the savefile to be updated during running (which is the usual default) a slow usb stick / SD card really does impact on the time that the system "locks up". Thats why I generally turn off the savefile update and only allow it at shutdown time. I also think that a really slow stick lengthens the save process significantly, and therefore increases the risk of data loss if the power fails, or if I get a bit careless and pull the stick before saving is finished.

Timing buffered disk reads: 26 MB in 3.78 seconds = 7036 kB/s
-------------------------------------------------------------------
Timing buffered disk reads: 146 MB in 3.00 seconds = 49717 kB/s
-------------------------------------------------------------------
Timing buffered disk reads: 13 MB in 3.01 seconds = 4412 kB/s
-------------------------------------------------------------------

Interesting variation in speeds. Several of my sticks are lucky to get beyond 1 or 2 MB/s even on a usb2 port. Pretty lousy - and very noticeable at write time.

I'm stunned at the differential you've posted for the EXT4. Amazing!