Re: Efficient way to import snapshots?

From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Jul 31, 2007, 15:50 UTC
Message-ID: <alpine.LFD.0.999.0707310845490.4161@woody.linux-foundation.org>
In-Reply-To: <20070731135332.GA58867@nowhere>

On Tue, 31 Jul 2007, Craig Boston wrote:

> 
> I just so happen to be rebuilding the zfs pool on that server this
> morning in order to add more swap, so your wish(1tcl) is my rcmd(3).

You, sir, are a total geek.

I'm not sure if that's a compliment or a curse.

Show 15 quoted lines

> Same machine, on a UFS filesystem (single disk, since zfs was doing the
> RAID), with the cache tuning parameters reset back to defaults:
> 
> First 'git status' after a reboot:
> git status  2.23s user 2.23s system 17% cpu 24.987 total
> 
> Second:
> git status  1.81s user 1.34s system 98% cpu 3.188 total
> 
> Third:
> git status  1.76s user 1.45s system 98% cpu 3.252 total
> 
> So I definitely think the problem is just that with its increased
> overhead, ZFS simply can't keep all the metadata in the cache with the
> available memory.

Very interesting. And thanks. The whole "ZFS is great" internet meme seems to be partly due to not a lot of people having used or compared it in real life. I'm sure it's wonderful for some things, but it clearly does have a lot of downsides too.

			Linus