SQL Server Performance Forum – Threads Archive
RAID 10 or RAID 5 for hughe DB
Hello Everyone I have to install a 200GB DB. Therefor I have a FibreCAT with 36 Hard disks + some HOT spare witch I have to configure. Sadly I have a Controler limitation to 6 Drives in one Array (I can only use one Channel). Now my plan is to install 6 array of 6 drives: 1 for the SQL Binary and tempDB1 for the LOG
4 Database files There are some other drives for OS and Backup so you don´t have to care. So far no problem, but should I choose RAID 10 or RAID 5. You have to know that I´m looking for the fastest solution but in benches the drives are nearly at the same speed. RAID 10 read
Drvpos 4kb16kb64kb1mb16mb
0%1026,548,687112
50%9,8244684102
98%9,825406881,6
RAID 10 write
0%4,512,826,546,850
50%4,512,925,947,149,5
98%4,512,726,847,448
RAID 5 read
0%11,828,859,4100132
50%11,828,159,8101,2130
98%11,827,855,299,8128
RAID 5 write
0%4,713,226,743,146
50%4,61326,643,648
98%4,71326,342,944,8 But this says nothing about accesstimes. What should i use. Thanks Azrael
There is differents oppinions about RAID is this Forum, so this in one of them. I suggest RAID 10, and if you can separate data than indexs in differents drives, much better. One question: database is more for read, writes or balanced? Luis Martin
Moderator
SQL-Server-Performance.com All postings are provided “AS IS†with no warranties for accuracy.
In some Microsoft testing, they have found that RAID 10 can be as much as 50% faster than RAID 5, depending on the hardware and application. If you can choose RAID 10, that’s the way to go. —————————–
Brad M. McGehee, MVP
Webmaster
SQL-Server-Performance.Com
Raid 10 is better (much better in write operations) But sometimes, the controller cache, can fool the benchmarks,
for example if your controller has 1GB, and you make a bench, that writes 700 MB
of information, you would not see any diference, cause all the writing occurs at controller
memory speed. If your app, will not surpass the controller cache at write time raid-5 is not a problem. But maybe one day, some upd operation will bring the machine down. It really depends on your
application behavior.
Also, if your disk subsystem is faster and has a large cache as cosaco mentioned then the overall capacity of your server backplane, it can become much less relevant what type of RAID you use. This can be the case many times when old servers are hooked up to really high-end SANs for example. Having said that, I would go with RAID 10 anytime I could afford it and need the guarantee of good performance, if choosing between that and RAID 5. MeanOldDBA
[email protected] When life gives you a lemon, fire the DBA.
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