Re: SSD recommendations
* Lubos Vrbka <lists@vrbka.net> [080830 10:31]:
> in the next couple of days, i should get a new notebook (dell d430)
> with 32gb SSD. i checked the web for suggestions regarding swap
> usage with SSD and the best filesystem, but the results i got are
> mixed - some suggest ext2, some suggest ext3, swap usage is also not
> clearly yes/no.
>
> personally, i probably shouldn't need swap - the machine will have
> 2gb of ram and my current notebook with 1gb works just fine (i just
> filed the ram once in the last two years - merely by accident).
>
> i'd be really grateful for any suggestions, experience, ... whatever
> you think might be relevant when working with SSD hard drives.
Not sure if my experience will be relevant to yours, but here's my
story of Debian on a Flash HD...
I've been running my ThinkPad X40 with the HD replaced with a 12GB
CompactFlash card (Sandisk Extreme III) using an IDE-CF adapter [1].
Mounting the filesystem with the 'relatime' option has been helpful.
Mostly I run text mode in a framebuffer console, where I noticed
issues with the display 'hanging'. For example, while moving the text
cursor in Vim, the cursor would sometimes freeze for 3 or 4 seconds,
then jump ahead the distance it would've moved while frozen. Or while
scrolling text in Less, the text would freeze then jump ahead in the
same manner. When switching between terminals in GNU Screen there
could be a several second pause...quite annoying.
This issue was largely resolved by by adding the 'relatime' option
in /etc/fstab like so:
/dev/disk/by-uuid/... / ext3 relatime,errors=remount-ro 0 1
I read about this on the Linux kernel mailing list [2], where there
was also mention of using the 'data=writeback' option. Didn't try
that, as it seems to come with a risk of data corruption (in the event
of a crash), and the relatime option had already solved my problem.
Didn't use 'noatime', as it could potentially interfere with Mutt's
ability to determine if there are new emails in mbox files.
I've thought about putting a second CF card into the CardBus slot
for emergency overflow swap, and to have a place to suspend to disk.
Not sure how much suspend to disk would hammer flash storage, but I
figured by restricting swap to one physical device, I could at least
know what got trashed by what. But that plan is on hold due to a bug
that prevents my PCMCIA/CF adapter from being recognized [3].
There's only 512MB RAM on my machine. Usage doesn't go above 120MB too
often, but it would be nice to have some emergency swap space, maybe
with a utility that could shut down a memory gobbling process once
it invaded swap space too aggressively...possible?
As far as ext2 vs ext3, can't say I have a definitive answer, but I've
been using ext3 on various CF cards & thumb drives for a couple years
now without incident.
Regards,
John
[1] AD44MIDE2CF IDE to 2 CF slots Adapter for Notebook
(note: only one slot is really usable...the 'slave' slot
is realllly slow, no DMA)
http://www.shopaddonics.com/itemdesc.asp?ic=AD44MIDE2CF&eq=&Tp=
[2] Linux: Replacing atime With relatime
http://kerneltrap.org/node/14148
Once upon atime
http://lwn.net/Articles/244829/
Replacing Atime With Relatime in the Kernel
http://linux.slashdot.org/article.pl?sid=07/08/08/1810243
[3] CF card not detected in PCMCIA adapter
http://lists.mur.at/pipermail/grml/2008-August/004066.html
--
John Magolske
http://B79.net/contact
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