touch-packages team mailing list archive

[James Troup <james.troup@xxxxxxxxxxxxx>]

"Theodore Ts'o" <tytso@xxxxxxx> writes:

> If you try to use more than 95% of the storage, performance will
> generally suffer -- badly.

Sorry, but why is that?  And do you mean read performance, write
performance or both?  And is that a factor of the type of storage
(e.g. spinning disk vs. SSD)?

> In addition for the root file system, you really do want to leave the
> default at 5% so that root can write to critical file systems.

Sure, I didn't suggest eliminating the reservation, just reducing it.
Or is there some reason that root would need at least 5% (as opposed
to 1% or 2%) of disk available to write to that I'm missing?

> And since the vast majority of Ubuntu users are using a single root
> file system, that implies that the for the vast majority of file
> systems created by Ubuntu, the default is in fact appropriate.

While that may be true of Ubuntu on the client (desktop, laptop,
tablet, phone, etc.); I'm not sure it's true of server and cloud?

-- 
James

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to e2fsprogs in Ubuntu.
https://bugs.launchpad.net/bugs/1340448

Title:
  5% reservation for root is inappropriate for large disks/arrays

Status in “e2fsprogs” package in Ubuntu:
  Confirmed

Bug description:
  mke2fs (and it's ext3 and ext4 analogs) still default to reserving 5%
  of the filesystem for root.  With the size of modern disks and arrays
  this isn't a terribly sensible default, e.g. if I have a 10Tb array,
  mke2fs will reserve 500Gb for root.

  Obviously this is both tunable at FS creation time and fixable after
  the fact but I still think we should try and improve the defaults.

  Given the size of modern disks, I think it'd make sense to either a)
  only reserve a smaller amount (e.g. 1%) or b) reserve n% if the
  filesystem is << NNN GB and otherwise reserve NN GB.

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