Mario Goebbels wrote:
While setting up my new system, I'm wondering whether I should go with plain
directories or use ZFS filesystems for specific stuff. About the cost of ZFS
filesystems, I read on some Sun blog in the past about something like 64k
kernel memory (or whatever) per active filesystem. What are however the
additional
costs?
I don't think the resource costs are well characterized, yet.
IMHO, you should only create file systems if you need to have different
policies for the file systems. Search this forum for more discussion on
this topic.
The reason I'm considering multiple filesystems is for instance easy ZFS backups
and snapshots, but also tuning the recordsizes. Like storing lots of generic
pictures from the web, smaller recordsizes may be appropriate to trim down the
waste once the filesize surpasses the record size, aswell as using large recordsizes
for video files on a seperate filesystem. Turning on and off compression and access
times for performance reasons are another thing.
compression and atime settings are policies.
recordsize could also be a policy, however, it seems to me that you are
confused about
ZFS and recordsize. The reason it exists is for those applications (eg.
databases)
which use a fixed recordsize and we want to match that record size to avoid
doing
extra work. For example, if the application recordsize is fixed at 8 kBytes,
then
we don't want to prefetch 129 kBytes (or 56 kBytes) as that could be wasted
work.
By default, ZFS will dynamically adjust its recordsize, which is probably what
you
want.
Also, in this same message, I'd like to ask what sensible maximum directory sizes
are. As in amount of files.
Dunno. In theory, you could go until you run out of space. Several people have
commented on their usage, so you can look in the archives.
-- richard
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