How does RAID 5 need 4 i/o's per disk? RAID 5 is slower because it must calculate a parity bit before writing the data to disk. If you have enough cache so that the OS thinks it is written before it is really done then that negates the performance hit of RAID 5. All controllers we use have 128MB cache and some large SAN systems may have GB's of cache. RAID 5 is optimal for reads. The more spindles the better by the way.
If you can afford it RAID 10 or 1+0 combines the benefits of RAID 1 and 0. I would never recommend using RAID 0 for anything on a server. Even if it is just a dev box you still have to consider lost labor hours while people can't work. Benchmarking is the only way to tell if you absolutely must have the optimal cost and performance solution. We use RAID 5 for all large configurations. RAID 1 only for the OS and transaction logs. -----Original Message----- From: Byron Kennedy [mailto:[EMAIL PROTECTED]] Sent: Monday, February 04, 2002 2:21 PM To: NT 2000 Discussions Subject: RE: SQL Server and RAID Levels not exactly: RAID 5 is the most costly on writes as it requires 4 physical i/o per disk per write (remember parity is distributed across all drives). RAID 1 requires 2 physical i/o per disk, per write. RAID 0 requires 1 physical i/o per disk per write. RAID 10 (0+1) requires 2 physical i/o per disk, per write. byron -----Original Message----- From: Szlucha, Chris [mailto:[EMAIL PROTECTED]] Sent: Monday, February 04, 2002 12:06 PM To: NT 2000 Discussions Subject: RE: SQL Server and RAID Levels Forgive me if I'm wrong, but Ed wasn't saying to use both RAID 0 and RAID 1, but rather what is sometimes called RAID 10, or more properly RAID 0+1. It is a mirrored RAID setup. Speed and redundancy, but it's the most costly of the bunch. And your statement about it being faster on RAID 0 or 1 is incorrect. RAID 5 is faster, as the write job is split up across the drives and each drive writes it's own piece of data at the same time as the others. -Chris -----Original Message----- From: Paul Timmerman [mailto:[EMAIL PROTECTED]] Sent: Monday, February 04, 2002 3:00 PM To: NT 2000 Discussions Subject: RE: SQL Server and RAID Levels It would all depend on the importance and size of the data. If there is going to be a large amount of data I would stick with thye RAID 5 for overall redundancy. In this case, I would recommend using 15K rpm drives if that is monetarily feasable. Yes, writing is a lot faster on RAID 0 or 1, but does this meet your redundancy needs? I would be very wary of placing the logs on a RAID 0 drive. That is NO redundancy. Again, depending on the importance of the data data, it might be okay. However, remeber that RAID 0 means that if that drive goes, so goes the transaction log and your ability to do a point in time recovery. >From: Ed Esgro <[EMAIL PROTECTED]> >Reply-To: "NT 2000 Discussions" <[EMAIL PROTECTED]> >To: "NT 2000 Discussions" <[EMAIL PROTECTED]> >Subject: RE: SQL Server and RAID Levels >Date: Mon, 4 Feb 2002 14:46:54 -0500 > >How about using 0+1 on the SQL Database. You get speed and redundancy at >the >price of space. Much faster then RAID5. > > >-----Original Message----- >From: Anthony L. Sollars [mailto:[EMAIL PROTECTED]] >Sent: Monday, February 04, 2002 2:40 PM >To: NT 2000 Discussions >Subject: SQL Server and RAID Levels > > >I am building another production SQL Server for our services team, and have >configured in my default configuration: >2 x 18gig SCSI on RAID 1 = OS & Pagefile >2 x 73gig SCSI on RAID 0 = Logs & tempDB >4 x 73gig SCSI on RAID 5 = SQL Database > > >The problem is the SQL engineers are questioning the performance of RAID5 >for their needs. > >We are using RAID 0 on the logs because this is transactional data that is >not important, and we don't need redundancy here just sheer speed. But they >are saying that RAID 0 should be used isntead of RAID5 on the 4 drive >array. >The bulk of the work on this RAID5 will be data manipulation, where they >willl run sql scripts that compress and organize the tables in the >database. >In my opinion RAID 5 is good for this also. > >-TOny >Thanks for any advice > >------ >You are subscribed as [EMAIL PROTECTED] >Archives: http://www.swynk.com/sitesearch/search.asp >To unsubscribe send a blank email to [EMAIL PROTECTED] > >------ >You are subscribed as [EMAIL PROTECTED] >Archives: http://www.swynk.com/sitesearch/search.asp >To unsubscribe send a blank email to [EMAIL PROTECTED] _________________________________________________________________ Join the world's largest e-mail service with MSN Hotmail. http://www.hotmail.com ------ You are subscribed as [EMAIL PROTECTED] Archives: http://www.swynk.com/sitesearch/search.asp To unsubscribe send a blank email to [EMAIL PROTECTED] ------ You are subscribed as [EMAIL PROTECTED] Archives: http://www.swynk.com/sitesearch/search.asp To unsubscribe send a blank email to [EMAIL PROTECTED] ------ You are subscribed as [EMAIL PROTECTED] Archives: http://www.swynk.com/sitesearch/search.asp To unsubscribe send a blank email to [EMAIL PROTECTED] This e-mail and any files transmitted with it are confidential and are intended solely for the use of the individual or entity to whom they are addressed. 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