DL380 G5 Array Advise

[Darren Etheridge_2]

I just received a DL380 G5 with 7 drives in the array. I was wondering what is the best way to setup the root/boot drives (Windows 2003 Enterprise Server). I am used to having dedicated root/boot drives and a seperate array for data drives, but the default is to setup the boot drives from the array (with a Logical drive from the array).

This system will also be a SQL 2005 DB Server.

Would setting up the boot volume for Windows be fault tolerant if I just took a 65GB slice of the RAID 1/0 for the OS and use the remainder for the SQL DB.

For fault tolerance, do I need to setup one of the drives to be a hot spare?

Any help/advise would be appreciated.

[James Kennedy_5]

Depends on if the Database server is going to be hammered intensively or just a standard database usage.

Disk writing to RAID 1 is best for performance, so a real high end SQL Database server would have a RAID1 volume for the Databases and another RAID1 for the logs. It would also be beneficial to attach the database array to a separate array controller with a large amount of write cache.

Disk space is also a factor, if you need all the space, then a simple RAID5 with all 7 drives will work pretty fine, with slightly reduced performance.

If the high-end disk write performance isn't a requirement, then RAID5 or a split of RAID1 for the OS and RAID5 for database/logs will work too.

Hope this is helpful and not too confusing.

[dms_1 · Accepted solution]

I think that RAID1 for the OS (2hdd's) and RAID5 for database/logs (5 hdd's) is the best choice.

You dont need a hot spare for fault tolerance, the RAID is fault tolerant by himself.Hot spare means that if, for example, one of your OS HDDs in RAID 1 fails, the 2nd will start rebuilding on the hot spare.If you do not have a hot spare the logical drive will be degraded but still functional and you will have to replace the failed HDD to start the rebuild.

For additional info see the ACU user guide:

http://search.hp.com/redirect.html?type=REG&qt=array+configuration+utility+user+guide&url=http%3A//docs.hp.com/en/9320/acu.pdf%3Fjumpid%3Dreg_R1002_USEN&pos=1

[Patrick Terlisten]

Hello,

I won't use RAID 5 for databases, because databases do often "short writes". A logical write IO on a RAID 5 will result in two read (block to change and parity), the recalculation of the new parity block, and two write IOs (write new block and new parity block). Every parity-based RAID suffers under this "write penalty". Better use four disks in a RAID 1+0 and one global hot spare for your databases. Also you should use a battery backed write cache module for you Smart Array controller. Otherwise the controller will disable the write cache.

Hope this helps.

Best regards,
Patrick