Incorrect partition creation when on an SSD (EXT3 instead of EXT2)

[jamescridland]

I'm using a little Acer Aspire One with an 8G SSD drive, which works well with Ubuntu 8.10 Intrepid Ibex.

However, on installation (from the 'live CD' downloaded a week ago), the partition manager set me up with an EXT3-formatted SSD drive. A journalled EXT3 system uses the SSD drive much more than a EXT2 formatted system; and I was experiencing severe slowdowns when doing filesystem-heavy things - particularly when, for example, running software updates or using Firefox 3.

All the advice I've read suggests setting up Ubuntu, on a solid-state flash drive, using EXT2. Having now done so, the system is much nimbler and much faster.

Assuming that people here agree with this, I'd therefore like to submit that the installation process is incorrectly installing an EXT3 filesystem for a solid-state hard drive; and therefore that this is not desired behaviour.

(As an aside, I got hopelessly confused when attempting to override it and choose EXT2; but thankfully found a guide to simply change my EXT3 formatted drive to an EXT2 one.)

I'm unclear what more information you require to help fix this bug; but I would see the current crop of SSD-based systems such as the Acer Aspire One and the Asus Eee PC family computers as being important machines to fully support in an out-of-the-box 8.10 experience.

[Dimitrios Symeonidis (azimout)]

just to clarify: your suggestion is that the ubuntu installer automatically uses ext2 when installing to an ssd?

also, during installation, which method of formatting did you choose? (manually, guided, etc)

[jamescridland (james-cridland)]

I chose "guided".

And yes, my suggestion is that the Ubuntu installer automatically uses EXT2 when installing to an SSD - rather, that its choice of EXT3 for an SSD is incorrect.

[Dimitrios Symeonidis (azimout)]

now we need to see if there's actually a way to tell if the underlying storage device is magnetic or solid state...

[Colin Watson (cjwatson)]

Being able to detect it would make it relatively straightforward to fix in the manual partitioner. It'd still be an utter pain in the automatic partitioner because ext3 is hardcoded in the recipe files. I'm not even sure where to start here ...

[Colin Watson (cjwatson)]

(Marking as low simply because I'm not sure whether we'll get to this any time soon. It seems that manual partitioning is the most practical solution for the time being. I'm interested in how you got confused when trying to choose ext2 instead; it ought to be fairly straightforward in the manual partitioner.)

[Dimitrios Symeonidis (azimout)]

thanks colin.

james said he chose guided, not manual.

[Jiri Bajer (sarimak)]

Colin: ad detection of SSD - in my eee 901 it's shown in hdparm:

$ sudo hdparm -I /dev/sda | grep Model
 Model Number: ASUS-PHISON SSD

OTOH dmesg doesn't show any SSD-specific messages...

ad settings for SSD: I'd vote for mount -o noatime,commit=60 and
vm.swappiness=0
vm.dirty_background_ratio=1
vm.dirty_ratio=40
vm.dirty_writeback_centisecs=6000
or similar in /etc/sysctl.conf

[jamescridland (james-cridland)]

Similar on this Acer Aspire One:

sudo hdparm -I /dev/sda | grep Model
 Model Number: P-SSD1800

...if this is useful

[Dimitrios Symeonidis (azimout)]

on one hand, using hdparm (or sdparm) might bring us closer to a solution
however, we definitely cannot depend on the model number for reliable detection (possibility of false negatives, and maybe even some false positives???)

[Dimitrios Symeonidis (azimout)]

ok, here's just an idea:
what if, as a temporary solution, we add one more choice in the installer's partitioner?
something like "Guided - Flash/SSD media - use entire disk"...
until we find a way to detect the type of media, that is...

[Colin Watson (cjwatson)]

Workaround for Jaunty: add the kernel parameter "partman/default_filesystem=ext2" when booting the installer.

There is other work in progress on detecting SSDs.

[Frederik Seidelin (frederikseidelin)]

I'm not sure that it would do anything but confuse the user, Dimitrios. You and I obviously know whether we have an SSD, but I don't think most people are aware of anything about their hard drive but the storage space -- I mean, 5400-RPM hard drives continue to exist and are even sold with Intel Core processors! If the user, who could also be one who'd scarcely even heard of netbooks, further reducing the likelihood that they have a clue about the difference between magnetic and flash-based hard drives, had to answer questions like that, they might stall and think Ubuntu is too technical. Especially if they were moving from Windows which "just "works""...

I don't have any better suggestions, though.

[kg (box-dev)]

I'm not sure that all SSDs should only be used with ext2. Early/cheaper JMicron-based SSDs have lots of issues with small writes which can cause big slowdowns, and certainly journalling wouldn't help for that. But there are now several drives that dont have anywhere near the same performance problems, and since SSDs are still an emerging technology really, I'd expect things to keep improving. Point is, just because someone has an SSD, doesn't mean they need to use ext2 to cut down on writes.