Upcoming filesystems?

Tom Arnold xyzzy at sysabend.org
Thu Feb 12 18:48:40 PST 2004

On Fri, Feb 13, 2004 at 10:20:10AM +0800, Xin LI wrote:
> Personally I'd prefer the SoftUpdates approach, so I am more interested
> in what made you to think it doesn't fit your needs, performance?
> security features? or others?

Boot time.  Large small-block filesystems take forever to come up at bootime
Forever being approx 10 minutes per filesystem for the snapshot to occur, with 3 filesystems on the machine it adds up.

If you go really insane on your block size on a large enough disk, in my
case 1TB disk, 4k block size, 2billion inodes, the snapshot will just error
out saying it doesnt have enough space.  This isnt as much of an issue as
we've determined the average filesize to be markedly over 512 bytes and it
seems to handle 8k/1k just fine, but I can see this sneaking up on someone
as drives get larger and larger...

Minor issue, there are times when you cannot remove a file or subdirectory
while the bgfsck is running.  Important to us because of how the space is
being used.

Has to be large numbers of small blocks/fragments because its an extreme
numbers of small files.  I may not agree with how its being done, but I have
to deploy a machine to handle it.  I can expect hundreds of millions of 1k
files on the each 1TB slice of a 3TB array.

The boot-time is whats really killing us.

Performance-wise, I've found softupdates to easily outperform ReiserFS.
 - Tom Arnold -       When I was small, I was in love,                  - 
 - Sysabend   -       In love with everything.                          -
 - CareTaker  -       And now there's only you...                       - 
 --------------         -- Thomas Dolby, "Cloudburst At Shingle Street" -

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