September 23, 2014 at 12:22 pm
I am about to install SQL SERVER 2014 BI edition, 64GB ram, and have 8 disks for 80% reads.
What would be the better choice please?
(2) 4 disk RAID 10
or
(4) 2 disk RAID 1
I would prefer RAID 10, but wouldn't having just two tamper performance since I would have to share data files and tempd on same drive? Please let me know options or what you would prefer if you had this in front of you?
Thank you for responses / suggestions!
September 24, 2014 at 5:05 am
what size and speed are the disks
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"Ya can't make an omelette without breaking just a few eggs" 😉
September 24, 2014 at 8:45 am
I only know they are SAS drives, but different sizes. I have come aboard a company, but the system administrator holds the key to the server and is not sharing information. Even worse he installed SQL SERVER with all defaults. I do know that he currently has RAID 5 set up, but I have 2 drives I see in disk management and one is partitioned. The two drives I see show 450 GB and 1250 GB.
I just know he ordered to more SAS drives to have a total of 8 hard disks and he is dead set on RAID 10, but I was wondering if any advantage to splitting those 8 into (4) RAID 1.
Thank you for any information
September 29, 2014 at 11:26 am
R1 and R10 (mirror with stripe) have the same 2x write penalty. In my experience they're the most popular configurations for TempDB and .ldf LUNs.
R5 (stripe with parity) has a 4x write penalty and is more popular for .mdf/.ndf full text LUNs as it usually handles reads better.
September 29, 2014 at 2:56 pm
sqldriver (9/29/2014)
R1 and R10 (mirror with stripe) have the same 2x write penalty. In my experience they're the most popular configurations for TempDB and .ldf LUNs.R5 (stripe with parity) has a 4x write penalty and is more popular for .mdf/.ndf full text LUNs as it usually handles reads better.
Actually RAID 5 is pretty poisonous if you ever have a disc failure - the performance penalty during recovery is very large, recovery takes a very long time, and a second disc failure before recovery from the first is complete is a disaster. So RAID 10 is generally preferred to RAID 5 even with read-intense workloads if very high reliability is required.
For READ-intensive workloads a given throughput is usually cheaper with RAID 5, but there is a significant reliability loss. But for most people the reliability of RAID 5 is acceptable, provided the configuration includes a hot spare drive. 14 years ago I was specifying RAID 10 for everything but database, and RAID 5 for database. 10 years ago in a different place I was switching the configuration rules for new installations from RAID 1 for OS and RAID 5 for everything else to RAID 10 for everything (with the same number of discs but each disc having twice the capacity), because we had a serious reliability requirement. And despite our read-intensive workload that switch delivered a factor of 4 performance improvement, so not all read-dominated loads run better on RAID 5.
Tom
September 29, 2014 at 4:18 pm
With modern R10 controllers you actually get more for your buck. They are able to spread requests to multiple disks in the array to share the workload. This has a huge performance plus.
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"Ya can't make an omelette without breaking just a few eggs" 😉
September 29, 2014 at 4:28 pm
Let's just put it all on flash!
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