Re: [9fans] fossil pb: FOUND!

["Aram Hăvărneanu" <aram.h@mgk.ro>]

> content addressed means given the content, you can generate the address.
> this is NOT true of zfs at all.

How come? With venti, the address is the SHA-1 hash, with ZFS, you get
to chose the hash, but it can still be a hash.

> you keep changing the subject.  your original claim was that random
> access is not slower than sequential access for ssds.  you haven't backed
> this argument up.  the relative performance of ssds vs hard drives
> and caching are completely irrelevant.

My original claim was that fragmentation is a non issue if you have
SSDs.  I still claim this and I expanded on the context in my previous
post.  Of course that random I/O is slower than sequential I/O, SSD or
not, but in practice, filesystem fragmentation causes an amount or
random I/O much less than what a SSD can handle, so throughput in the
fragmented case is close to the throughput in the sequential case.

I don't think that caching is completely irrelevant.  If I have to
chose between a complex scheme that avoids fragmentation and a simple
caching scheme that renders it irrelevant for a particular workload,
I'll chose the caching scheme because it's simpler.

-- 
Aram Hăvărneanu