Re: HP9000+LVM+Online

> There is no problem using LVM with Informix, either raw or cooked. As > you can see from previous posts, it is in use and it has been tested > extensively. As always, depending on your specific configuration ( > including > kernel, LVM, and Informix configuration) the performance characteristic > will vary. I tried to email you about this but it got bounced back. As you may have seen from my postings I have had some pretty disastrous experiences with LVM and - much more so - RAID architectures on HP kit. On the other hand, I have also had sight of documents claiming RAID to be the absolute dog's -------- (sorry, British topical cliche meaning "the very best") in conjunction with RDBMSs, but have never witnessed any proof. In spite of numerous mildly-provocative postings in this conf, I have yet to receive a response which has a kind word to say about RAID or LVM. The V6.00 OnLine manual devotes a page to LVM but doesn't seem to come up with anything kinder than along the lines of "(mostly) harmless" With more and more oems pushing out such architectures, I think it's important for any of us involved with OnLine to gain an understanding of the ups and downs of LVM and RAID, the hows and how-nots to do it. As I understand it (and all my experiences prove it), the way to configure OnLine is with as many separate raw devices as possible. Cut across the grain of that and you're well into the brown sticky stuff performance-wise. The most graphic case I ever came across was where a very high-profile UK site got their checkpoint times down from 18 seconds to well under a second simply by ripping out RAID 3 and LVM. And that was on a quiet, low-load system. I was talking to their solutions provider today and they confirmed that they have continued to give that stuff a very wide berth, to good effect. Please will you beg to differ, present the case for the defence, in as much detail as possible, to put the record straight. I would love not only to be proved wrong, if possible, but to understand exactly why it didn't work for my customer. akent@cix.compulink.co.uk (Andy Kent) -------------------------------------