Celso wrote:
a couple of points
One could make the argument that the feature could
cause enough
confusion to not warrant its inclusion. If I'm a
typical user and I
write a file to the filesystem where the admin set
three copies but
didn't tell me it might throw me into a tizzy trying
to figure out why
my quota is 3X where I expect it to be.
I don't think anybody is saying it is going to be the default setup. If someone is not comfortable with a feature, surely they can choose to ignore it. An admin can use actual mirroring, raidz etc, and carry on as before.
There are many potentially confusing features of almost any computer system.
Computers are complex things.
I admin a couple of schools with a total of about 2000 kids. I really doubt
that any of them would have a problem understanding it.
More importantly, is an institution utilizing quotas really the main market for
this feature. It seems to me that it is clearly aimed at people in control of
their own machines (even though I can see uses for this in pretty much any
environment). I doubt anyone capable of installing and running Solaris on their
laptop would be confused by this issue.
Its not the smart people I would be worried about. It's the ones where
you would get into endless loops of conversation around "But I only
wrote 1MB how come it says 2MB?" that worry me. Especially, when it
impacts a lot of user level tools and could be a surprise if set by a
BOFH type.
That said I was worried about that type of effect when the change itself
seemed to have low value. However, you and Richard have pointed to at
least one example where this would be useful at the file level....
Given a situation, where you:
a) have a laptop or home computer which you have important data on.
b) for whatever reason, you can't add another disk to utilize mirroring (and
you are between backups)
this seems to me to be a very valid solution.
... and though I see that as a valid solution to the issue does it
really cover enough ground to warrant inclusion of this feature given
some of the other issues that have been brought up?
In the above case I think people would me more concerned with the entire
system going down, a drive crashing, etc. then the possibility of a
checksum error or data corruption requiring the lookup on a ditto block
if one exists. In that case they would create a copy on an independent
system, like a USB disk, some sort of archiving media, like a CD-R, or
even place a copy on a remote system, to maintain the data in case of a
failure. Hell, I've been known to do all three to meet my own paranoia
level.
IMHO, It's more ammo to include the feature but I'm not sure its enough.
Perhaps Richard's late breaking data concerning drive failures will add
some more weight?
_______________________________________________
zfs-discuss mailing list
zfs-discuss@opensolaris.org
http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
