So to answer the previous question, and ask one: was disk the most expensive component of the solution, Al?
I think if you're a small company (what's the definition of "small company" these days?) that investing in your own email system is a tough decision anyway you look at it. If you require high availability, disk is likely the least of your concerns if you can provision disk at pennies per MB for high performance disk. The other layers of the solution stack will cost you FAR more than your disk subsystem and frankly, I don't see lowering the cost of my low-cost resources a real factor to sway my decision. As I mentioned before, the difference in price is about 8K USD at unit one retail over the web pricing; Casual glance. I'd be willing to bet even money that your network, backup, training, active directory, software and people costs will far outweigh that 8K difference. In other words, disk is not my expensive resource in most cases and if I get into a situation where disk is the problem it cost me way more. (side story: somebody was telling me the other day about a line of business that generates .25 of all revenue for the company and used that as the reason we should listen to and cater to them as an IT org. I asked the obvious question: how much does it cost us for each of those quarters? Moral: I'm not impressed by up front costs. I've been doing this too long and know that there are other factors to consider such as TCO). Al: before jumping on the NAS bandwagon for Exchange and SQL and other db technologies, let me ask you this: After this investment, is it worth it to shave 8K off the overall price to get slower, commodity space-centric positioned storage for your mission-critical database app? SCSI was recommended because it tends to be more mature and faster (15K RPM drives etc) and more scalable than other technologies at the moment. SATA drives are primarily designed for space vs. speed while allowing for RAID configurations. NAS devices are the same: designed for provisioning large quantities of space vs. high-performance IOPS. That gap is closing, and certainly in the low end implementations the gap is much narrower and more academic than a high-end solution high-performance solutions would be. It's still there however. I note in Al's post that he mentions Veritas clustering vs. MSCS clustering. He's opted to go with options that Veritas could offer that Microsoft did not in it's own offering such as on-the-fly disk expansion. Bet it was cheap. </sarcasm> We all know that we can provision 6TB of "space" pretty easily in this day and age. Heck, I can provide that amount of space in DAS configurations if I wanted. NAS just makes it easier "out of the box". SAN is required at the moment if performance is an issue. As to the other question, if you're deploying an apathetic Exchange server (why?) then you're going to be fine deploying logs and db's on the slower NAS devices. Sure, you'll get some performance hits here and there, but it's a small price to pay for that 8K in your pocket, right (think TCO and think what the loss in opportunity costs are if your system is unusable)? Keep in mind that Exchange has roughly four types of I/O patterns going on at the same time. DB's = 70/30 random R/W, Logs= 2/98 sequential R/W (backups and commits to DB cause the read I/O; otherwise it's sequential write), queues = 1/7 R/W (write ratio increases with message size), and the temp file I/O = 1:1 random for the most part. That's without other applications of course, which change the pattern in unique ways. That being the case, if you have low I/O requirements, i.e. you have low user density you may be able to put the load on the NAS device and receive the performance you intend just as you might put the entire server on one 3 disk RAID five configuration in some implementations (I don't like that, but I like more user dense servers as a rule). Keep physics in mind and understand that rotational latency, disk contention with other apps, and other factors influence your performance since Exchange is so disk dependent for performance. As was previously mentioned, if you decide to use iSCSI, you should also worry about network latency. General rule: To prevent corruption in the database ensure reliable and timely disk IOPS - two-phase commit databases don't like flaky, slow, or otherwise unreliable IOPS. If your budget is so close that 8K (USD) is going to make or break you, consider outsourcing the messaging subsystem and save the headache and learning you'll no doubt have to go through and instead focus on your core business. Be sure to put in an availability clause with the ASP. And whatever you do, define your requirements thoroughly prior to spending ANY money or coming up with any solution. It'll help to direct you to the solution you want or possibly help you save enough that you can buy those bamboo slivers you've been wanting. My $0.02 anyway. I've already been informed I've lost my Dining Services MVP status, so this might be my last post on this subject as I can't afford to lose my wits. ;) -Al -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Al Garrett Sent: Thursday, July 29, 2004 2:28 AM To: [EMAIL PROTECTED] Subject: RE: [ActiveDir] OT: NAS and WSS I tried to read through most of the thread before answering. IRT Deji's comments regarding SAN-based, clustered Exchange: We run a 6Tb SAN, fiber-attached to several UNIX and Win2K Clusters (Veritas Clustering) The Exchange drives (databases) sit on the SAN and are presented to the three Exchange servers, appearing to them as ordinary internal hard drives. The servers are too dumb to know difference. Disk size can be expanded on the fly with Enterprise Volume Manager. Need more space? Add another 100 Gb. With an any-to-any clustering scenario, if an E2K server fails, the data is gracefully removed and presented to the failover cluster in a matter of minutes (maybe 2mins tops). BUT....this SAN was mighty pricey and required a pretty steep learning curve for those of us who had never driven one before. We also have a 400Gb+ NAS (HP) that serves up basically static content (Blackboard Learning System) and with Gb NICs it runs pretty sweet, especially connected to a Gb Cisco switch on a fiber backbone. This is a small form factor (5 1/2") desktop device that stores 1Tb using Firewire or USB 2.0 http://www.ecost.com/ecost/shop/detail.asp?DPNo=356797 You HAVE to see the cost.....unbelievable. AL -----Original Message----- From: Noah Eiger [mailto:[EMAIL PROTECTED] Sent: Wednesday, July 28, 2004 10:22 PM To: [EMAIL PROTECTED] Subject: RE: [ActiveDir] OT: NAS and WSS You guys are too funny. If the choice were between Leno and reading some of the posts on this list, I think I would take this list. Come to think of it, if the choice were between getting bamboo shoved under my nails and watching Leno, I might just choose the former. Well, needless to say, I got lots of laughs out of this thread. But basically, I regret a bit including the bit about Exchange. Though the discussion led me to wonder, would you put the database on the NAS or the logs? Or both? Is it the disk subsystem on a NAS that causes the concern or the connectivity? I suppose finally, after dealing with all the foo, does NAS really lower your true cost per gigabyte? Oh, just so I don't lose site of the original question, you all seem to be in consensus that if budget allows go DAS and go SCSI. NAS is ok for file sharing, particularly with directories that are infrequently accessed or just read from. (I may be summarizing some Google findings here as well). Do I have that basically right? nme List info : http://www.activedir.org/mail_list.htm List FAQ : http://www.activedir.org/list_faq.htm List archive: http://www.mail-archive.com/activedir%40mail.activedir.org/ List info : http://www.activedir.org/mail_list.htm List FAQ : http://www.activedir.org/list_faq.htm List archive: http://www.mail-archive.com/activedir%40mail.activedir.org/ List info : http://www.activedir.org/mail_list.htm List FAQ : http://www.activedir.org/list_faq.htm List archive: http://www.mail-archive.com/activedir%40mail.activedir.org/
