SQL Server Performance Forum – Threads Archive

SCSI Considerations

Hi All! I’m in the process of putting together a new SQL server, and have a few questions regarding the SCSI conf. that i hope some of you can help me with. I’ve come up with a solution that looks something like this: Dual Xeon 3GHz 4GB RAM 6 * 73GB 15k RPM Ultra320 disks With a disk setup like: Array1: RAID1 – OS/Appl Array2: RAID1 – SQLData Array3: RAID1 – SQLLog The SQL server will be hosting multiple (not many) databases (Full Recovery). Will i gain anything in performance by choosing a Dual Channel RAID ctrl. instead of Single Channel? Have my eyes on Adaptecs 2200S (Dual) and 2120S (Single) and if i didn’t have time to think i would say "Dual", but as i’m on a tight budget i don’t wan’t to waste my money. (And i have time to think… up a couple of questions for you <img src=’/community/emoticons/emotion-5.gif’ alt=’;-)’ /> Suggestions and comments are more than welcome. Thanks. – /Sune

With this configuration of Array, I don’t think you will gain to much with Dual Channel (Price/Performance).
But, I you think you will have heavy database, size and use, then Dual will help.
Also, if you are considering to split data in one Array and Index in other, Dual will help a lot. Of course, wait to others members oppinions. Luis Martin
Moderator
SQL-Server-Performance.com All postings are provided â€œAS ISâ€ with no warranties for accuracy.

Luis, Thank you for replying. <blockquote id="quote">quote:<hr height="1" noshade id="quote">With this configuration of Array, I don’t think you will gain to much with Dual Channel (Price/Performance).<hr height="1" noshade id="quote"></blockquote id="quote"> There’s perhaps a small chance of getting 2 more disks. If i were to be that lucky, i was thinking of placing the SQLLog on a RAID 1+0 (or is it 0+1?). Comments on that? <blockquote id="quote">quote:<hr height="1" noshade id="quote"> But, I you think you will have heavy database, size and use, then Dual will help. <hr height="1" noshade id="quote"></blockquote id="quote"> I’ve got the feeling that these dbs only are puppies (no, kittens) next what i’ve read about here. <img src=’/community/emoticons/emotion-1.gif’ alt=’

‘ /> Probably 5-10 dbs ranging from 50MB to 8GB. Only one above 3GB. This is also the one that will be used the most and quite a lot. Also the one used, when everyone complains about the performance. <blockquote id="quote">quote:<hr height="1" noshade id="quote"> Also, if you are considering to split data in one Array and Index in other, Dual will help a lot. <hr height="1" noshade id="quote"></blockquote id="quote"> Erhm…? *wush* I guess i won’t be doing that. <img src=’/community/emoticons/emotion-1.gif’ alt=’

‘ /> Really don’t know much SQL. Thanks again. – /Sune

Is good idea to put log in other Array. Any database (if no one design in different way) has data and index in one filegroup, PRIMARY.
So, all data will in one Array.
Is easy to create one o more filegroups (secondary, sune, free name) in other Array and then put indexs on new filegroup.
So you have data in one filegroup, one channel, and indexs in other filegroup, other channel.
In this way performance will better, because SQL can read in paralel way both disk. Luis Martin
Moderator
SQL-Server-Performance.com All postings are provided â€œAS ISâ€ with no warranties for accuracy.

What benefit do we get by striping the log data? We hardly read it other than in rollback, right? So why do you want to place the log on 0+1 array or 1+0 array? I think RAID 1 array should be good for log as it will give you same write performance as 0+1 or 1+0 configurations and also it will cost you less compared to the other configurations.

rlahoty, Well… I could be wrong, but i have always thought that the transactional logfiles should be placed on the fastest disks. Likewise for an Exchange database. Writes go to the logfiles first, and those are then committed to the DB afterwards. (roughly) Am i totally off track with this? Dunno how much the logfiles er used for reads, though.
Perhaps the best setup depends on whether it’s a read-mostly og write-mostly DB!? Now i’m confused.
What IS best practice? Thanks. —
/Sune

Check same subject: http://www.sql-server-performance.com/forum/topic.asp?TOPIC_ID=3925
http://www.sql-server-performance.com/forum/topic.asp?TOPIC_ID=2233
Luis Martin
Moderator
SQL-Server-Performance.com All postings are provided â€œAS ISâ€ with no warranties for accuracy.

Sune, I agree that transaction log should be placed on the fastest disks but I don’t think you get any benefits by placing them on 1+0 array or 0+1 array. You should be able to get same performance by placing them on RAID 1 array. That was my whole point. Thanks

RAID 10 performs significantly faster than RAID 1 actually for heavy write environments, which describes transaction log backups perfectly. It uses the disks much more efficiently for write performance. MeanOldDBA
[email protected] When life gives you a lemon, fire the DBA.

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