[gentoo-user] more tripleE SSD fs controversy

[gentoo-user] more tripleE SSD fs controversy

[Maxim Wexler]

Hi group,

More and more I'm coming across references to "cheap" ssds in the EEEs.

http://www.hohndel.org/communitymatters/eeepc/best-filesystem-choice-for-the-eeepc/

recommends ext2. Which I found surprising, but the guy seems knowlegeable.

Here is Theodore T'so:

# mke2fs -t ext4 -E stripe-width=32,resize=500G /dev/ssd/root

In his discussion of formatting the pricy Intel product. He doesn't
say if this would be worthwhile for the "cheap" type.

hohndel doesn't specify any options, just says, use ext2. What does
the group recommend?

Maxim

Re: [gentoo-user] more tripleE SSD fs controversy

[Robert Bridge]

Maxim Wexler wrote:
> Hi group,
> 
> More and more I'm coming across references to "cheap" ssds in the EEEs.
> 
> http://www.hohndel.org/communitymatters/eeepc/best-filesystem-choice-for-the-eeepc/
> 
> recommends ext2. Which I found surprising, but the guy seems knowlegeable.
> 
> Here is Theodore T'so:
> 
> # mke2fs -t ext4 -E stripe-width=32,resize=500G /dev/ssd/root
> 
> In his discussion of formatting the pricy Intel product. He doesn't
> say if this would be worthwhile for the "cheap" type.
> 
> hohndel doesn't specify any options, just says, use ext2. What does
> the group recommend?
> 
> Maxim
> 

Theodore T'so is playing with Intel SSDs if I recall correctly, which 
are in a totally different class to what you get in EEEs, like they cost 
about the same as the EEE does. His recommendations are based on a SSD 
with good built in wear leveling, and fast read/write performance.

ext2 is normally recommended for "cheap" SSDs such as are in the EEE 
because it is a non-journalled FS, which is kind of important when your 
disk has severely limited write life.

At least, that is my understanding of the situation
RobbieAB

Re: [gentoo-user] more tripleE SSD fs controversy

[Maxim Wexler]

>
> ext2 is normally recommended for "cheap" SSDs such as are in the EEE
> because it is a non-journalled FS, which is kind of important when your
> disk has severely limited write life.

It's not just the write life I'm worried about; it's booting into a
system whose partitions no longer line up, as recently happened
following an attempt to emerge mozilla-firefox.

mw

Re: [gentoo-user] more tripleE SSD fs controversy

[Walter Dnes]

On Fri, Jun 05, 2009 at 02:41:33PM -0600, Maxim Wexler wrote

> hohndel doesn't specify any options, just says, use ext2. What does
> the group recommend?

  This is in the context of "cheap SSD" diask drives.  They behave
differently from hard disks, so "everything you know is wrong" if you
try stuff that applies to harddrives.  You want to minimize the number
of writes to disk as much as possible, for 2 reasons...

1) Cheap SSD disk drives are atrociously slow.  The fewer unnecessary
writes, the more responsive the machine will be.

2) Cheap SSD disk drives are liable to wear out after a lot of writes.
Fewer writes means a longer lifetime for the drive.

  This brings us to the question of exactly how to minimize writes.  I
suggest ext2fs with the "async" and "nodiratime" and "noatime" options.

* journalling file systems pound away continuously at the journal file.
  As Martha Stewart would say... "that is not a good thing" for cheap
  SSD drives

* async is the default, but it doesn't hurt to list it.  It says not to
  do a separate write for each request, but to do writes in bigger, and
  less frequent, batches.  The "mount (8)" manpage has this to say about
  sync...
> In case of media with limited number of write cycles (e.g. some flash
> drives) "sync" may cause life-cycle shortening.

* nodiratime says not to update directory inodes when accessed.  You do
  need to specify it, because it is not the default

* noatime says not to update file inodes when accessed.  You do need to
  specify it, because it is not the default.  I don't know if "noatime"
  implies "nodiratime", but I'd play it safe and specify both.

-- 
Walter Dnes <waltdnes@waltdnes.org>

[gentoo-user] Re: more tripleE SSD fs controversy

[ABCD]

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Walter Dnes wrote:
> * nodiratime says not to update directory inodes when accessed.  You do
>   need to specify it, because it is not the default
> 
> * noatime says not to update file inodes when accessed.  You do need to
>   specify it, because it is not the default.  I don't know if "noatime"
>   implies "nodiratime", but I'd play it safe and specify both.
> 

"noatime" does imply "nodiratime", per various posts on lkml, so you
don't need both.
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