January 14, 2003 at 7:23 pm
Anyone using this? We use Dell hardware and they partner with EMC, so logical choice for a SAN. We're going to be clustering 2-3 servers, connecting all to a SAN, looking at initially acquiring 15-36g drives. Anyone using the 73g drives? Price difference is substantial! Comments on SAN tuning, performance?
Andy
January 15, 2003 at 5:08 am
Well of course the partnership between Dell and EMC is relatively new, so I would instantly ask who will be supplying maintenance contracts etc. That aside, the next subject to consider is performance. I have seen comments here in the past as I'm sure you have where people have complained about poor results when SQL files are placed on a SAN. From my own experience, where I had a Poweredge development system and a MTI fibre channel array, the results were mixed, a lot of random updates tended to be quicker, although my drives were configured as RAID5, so it can get subjective. In other words, aside from using the EMC hardware, there is then the fabric connections to consider and then also the configuration of the drives within the enclosure. A lot of variables - perhaps Dell could demonstrate your set-up at another site? I know in the UK, Dell had no other clients using an EMC array when I made active enquiries, but they could demonstrate a federated server system - which I would have thought a rarer requirement.
My connection was only 1Gbit/sec, I know things can go faster now; and as I mentioned above, you can partition your drives in various ways, such as mirroring and grouping. Which type of drives are you thinking of? Generally we tend to suggest that more spindles equals better performance, but then with caching and other clever stuff, having higher capacity drives with therefore higher data densities may offset this.
Sorry I haven't been a lot of help, but then you're at the leading edge somewhat.
Incidentally, have you considered a solid state storage system, which I believe would give you ultimate performance, at least at the moment?
January 15, 2003 at 6:29 am
Havent considered solid state. We've been using a Dell 650 for..a year maybe, good performance, no issues. We're conservative about hardware, better to have too much than too little! I've seen good comments about SAN's too, people saying they really rendered file placement irrelevant.
Definitely agree about spindles, at the same time you want to keep the drives 50% or so free, perf degrades as they fill. They have 36g/10k, 36g/15k, 73g/10 drives that will work. Price is an issue, so probably go witk 36k, not sure of speed - again, price matters.
Right now I've got the 650 with 10 drives, one used for hot spare, rest RAID5. Another server using 15 SCSI (man, talk about cheap - was maybe $7k!). Third server using 3 or 4 drives RAID-5. Thinking I need to maintain the # of spindles, though could probably go less on the one that is using SCSI.
Cabinet holds 15, so thinking one full plus at least 5 in second enclosure.
Dont know that I can post what the price is, but lets say we're talking $100-$200k for storage.
Andy
January 15, 2003 at 9:23 am
I've had experience with MTI's SAN equipment and with IBM FastT 700 equipment. MTI's first implementation of the Fiber SAN was slow and very picky. I received promises that there would be no way a Windows NT system with SQL 7 could demand more I/O than the system could give. I proved them wrong. That system was a V20. We then moved to their new fabric architecture called the s200. In both instances I used the 73GB drives. Tiny server room so I needed the density. The s200 was much better at handling I/O but we still had to be careful about balancing the data locations across the controllers and spindles. I have now moved to the IBM SAN FastT700 and am impressed. We don't have near the I/O issues as before and I now have 150 users hitting them constantly.
In all my dealings with SAN providers, I have discovered you have to be VERY involved in the process. Many times they will assume SQL Server will perform like UNIX based RDBMS and it doesn't. There are default stripe sizes they assume work for all scenarios and I have had better luck with some than others. In the first scenario, I didn't really understand the SAN environment and let the company do the design. I ended up having 90% of my I/O on 6 of the 24 drives.
If this is information you can use, I'd be glad to talk with you further.
Michelle
Michelle
January 15, 2003 at 4:10 pm
I may have some questions in a few days. Right now we're juggling a lot of different options based on projected growth and expansion vs what we have to work with. Interesting, but sometimes seems endless! Once I know what I'll probably be getting then I can start to work on how to best utilize it and what pitfalls await.
Andy
January 20, 2003 at 9:34 pm
"I have seen comments here in the past as I'm sure you have where people have complained about poor results when SQL files are placed on a SAN."
sjcsystems, can you elaborate on this?
A SAN with 2gb of cache and 2gb fiber worse than SCSI?
Anyone found this to be true?
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