Date: Wed, 11 Nov 1998 10:30:28 +1030 From: Greg Lehey <grog@lemis.com> To: Mike Smith <mike@smith.net.au>, hackers@FreeBSD.ORG Subject: Re: [Vinum] Stupid benchmark: newfsstone Message-ID: <19981111103028.L18183@freebie.lemis.com> In-Reply-To: <199811100638.WAA00637@dingo.cdrom.com>; from Mike Smith on Mon, Nov 09, 1998 at 10:38:04PM -0800 References: <199811100638.WAA00637@dingo.cdrom.com>
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On Monday, 9 November 1998 at 22:38:04 -0800, Mike Smith wrote: > > Just started playing with Vinum. Gawd Greg, this thing seriously needs > a "smart" frontend to do the "simple" things. Any suggestions? After seeing people just banging out RAID configurations with GUIs, I thought that this is probably a Bad Thing. If you don't understand what you're doing, you shouldn't be doing it. The four-layer concepts used by Veritas and Vinum have always been difficult to understand. I'm trying to work out how to explain them better, but taking the Microsoft-style "don't worry, little boy, I'll do it all for you" approach is IMO not the right way. > 4 x 4GB disks (2x Atlas, 2x Grand Prix) on an ncr 53c875, slapped > together as a single volume. (you want to mention building filesystems > in your manpages somewhere too - the '-v' option is not immediately > obvious). As Tony observed, it's in vinum(4). vinum(8) just describes the interface program. Do you still think I need to add more information? There's supposed to be a user's guide, when I get round to writing it. > 6:36 elapsed to newfs the 16GB volume in concatenated mode. 4:36 to > newfs it in striped mode (64b stripes). You shouldn't really be doing performance testing in this version. It's full to the gunwhales of debugging code. But I'd be interested to know how long it took to do a newfs on one of the disks without Vinum. > There was an interesting symptom observed in striped mode, where the > disks seemed to have a binarily-weighted access pattern. Can you describe that in more detail? Maybe I should consider relating stripe size to cylinder group size. > It will get more interesting when I add two more 9GB drives and four > more 4GB units to the volume; especially as I haven't worked out if I > can stripe the 9GB units separately and then concatenate their plex > with the plex containing the 4GB units; my understanding is that all > plexes in a volume contain copies of the same data. Correct. I need to think about how to do this, and whether it's worth the trouble. It's straightforward with concatenated plexes, of course. > Can you nest plexes? No. > Anyway, apart from one incident where I managed to get a pile of > debugger calls out of Vinum (freeing already free memory - it > occurred after many failed config attempts and I haven't been able > to reproduce it) If you do get it again, please don't hesitate. Take a dump. I'd like to find these problems. Having said that, I've been planning to rewrite the config code for a while. It's still a while off, but in the meantime please tread carefully. > it hasn't let me down yet. Tomorrow I build the world on it. Good to hear. I've built several worlds, including with degraded plexes, and so have others. I don't think you'll have any trouble there. > Thanks to Greg and the folks at Cybernet! You're welcome. Greg -- See complete headers for address, home page and phone numbers finger grog@lemis.com for PGP public key To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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