I realize there have been numerous discussions on server performance and RAID 1 vs RAID 5. In reading through prior postings I couldn’t find the answer I’m looking for so sorry if this problem has been discussed before. I’m one of those stubborn end users that sticks with RAID 5. Why? Because it’s save my behind twice now and have been able to continue conducting business before any tech support arrives. In our industry server downtime can equal customer compliance fines. At this point we’re running into periodic performance issues. Particularly while posting shipments/invoices. The cache gets full and them we get file locks when we should not and of course everything moves at a snail’s pace. Posting after the days business is not an option because we have to send EDI data on 80% of what we ship. My reseller is telling me that if I want the problem to go away I have to switch to RAID 1. His advice has been quite good up to now and I have no problem doing that if it’s going to work. So what I’m looking for is some feedback from you guys (and gals) and get your opinion. Will this correct my file lock problem? Perhaps there is some other tweek you can suggest that will help remedy my problem without going through the effort of reconfiguring the server… Here are our server spec’s: -2.8GHz P4 -1.5Gb RAM -RAID 5, 3x36Gb Drives Navision Database Info (not SQL): -16Gb used out of 25Gb -Cache set at 850Mb (any higher and the service won’t start) Thanks in advance for any advice.
Before You do anythin else go to RAID-1. I don’t know how many users You have. But with that database size I would go for a server with at least 8 pairs of disks. //Lars
Thanks Lars. I guess I just needed to hear it from someone else. 8 drives eh? Sounds like a lot. On a similar note, another recommendation I received from someone was to increase the server RAM to 3Gb and turn the windows page file (virutal memory) on the server down to the minimum. The concern is that part of the Navision cache may be in the page file and thus slowing things down further. We don’t use this server for anything but Navision. Any comments on that? Also, I cracked open the server case last night and found that our Adaptec card has no battery backup. This is not a concern because I also found that the cache is turned off. Not being a major hardware guy, how important is a cache on a RAID card?
OK. You will get a lot more performance than today even with 4 pairs in RAID-1. Then You have OS an exe’s on first pair and DB on three pairs (that is a total of 8 disks). Each DB-file will then hold approx 5Gb data which I think is to much. Try keep it under 3 GB = More disks. My previous advice with 8 pairs (=16 disks) would give You 2.3 GB in each database file which is perfect and will give You a LOT more performance than today. When it comes to cache You should never enable write cache even if You have a battery backup on the controller. Only use read cache. Putting 3GB Ram wont do any good. You can stay on 1.5Gb. With a cache in Navision on 800MB You will still have allmost 700MB left for OS which should be enough to avoid paging. There is a simple rule with Navision. Allways RAID-1 and a if You want performance: Buy a lot of disks. Dont bother so much about CPU or RAM. It’s all a matter of disk and network I/O.
Why do you recommend not to use write cache?
Raid 5 writes 2 bits as data and 1 bit as data checksum. Raid 1 writes 1 bit as data and 1 bit as data copy. So Raid 5 saves disk space (uses 66% against 50%), but loses write performance (checksum calculation takes processor time). Raid 10 (1+0) rules them all.
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Raid 10 (1+0) rules them all.
Nope. Not with Native DBMS. Then You should NOT use RAID-10 since You only get one commit cache. With Native DBMS allways use RAID-1. Never anything else. SQL is another issue.
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[Why do you recommend not to use write cache?
You can find some good stuff from David S. here: http://www.navision.net/forum/topic.asp?TOPIC_ID=7492
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Originally posted by Lars Westman
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Raid 10 (1+0) rules them all.
Nope. Not with Native DBMS. Then You should NOT use RAID-10 since You only get one commit cache. With Native DBMS allways use RAID-1. Never anything else. SQL is another issue.
Isn’t there always ONE commit cache? All slave.exe share the same memory,… Or not? Bostjan
Yes, if you use task manager you see the same size for all slave.exe
Yes. They share the same memory, but they are different processes where the DBMS can queue up transactions. Read the appendix in the developers guide on the CD. It’s all there. There is also an benchmark made by Navision and IBM that states that C/SIDE DBMS scale linear up to 8 separate physical disks. That’s just the facts. Navision want’s separate physical disks. And If You want redundancy You also put mirrors on these (RAID-1).
I want to thank everyone for their input. To follow-up, we just implemented a new server going from 3 RAID 5 drives to 8 RAID 1 (4 pairs). We also downgraded (due to cost) from Ultra 320’s to Ultra 160’s. We have seen a 6x improvement in speed…amazing. Thanks again.
Hi everyone, I’m a newbie in Navision Development and I have to admit that this user group forums have been more than helpful in getting me more accustomed to the principles and neccesities of Navision. As we speak, I have to set up 5 companies within 1 database, using SQL server. So from what I read in this topic, setting up the server with RAID is almost compulsory. Could someone provide me with more specific details on a standard server setup that would ensure acceptable performance…? Thanks in advance for any advices given [^]