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Best configuration for my database system
Hi friends,
in the EQL RAID settings, I always know the automatic.
However, I have dedicated LUNs for a SQL database.
On these LUNs could I configure to use a RAID that would provide better performance for these LUNs?
Setting the LUN block I always keep default (512bytes). I read that for the database the indicated one is to use 64K. That's true? Really better performance?
Why not use 64K for all LUNS since performance will be better?
Thank you.
dwilliam62
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December 20th, 2018 06:00
Hello,
I'm guessing you only have one EQL array? Is that correct?
Each physical EQL array "member", the entire enclosure, controllers and disks can only have ONE RAID type.
RAID10, RAID6, etc...
If you had more than one EQL array, you can set it at a different RAID level. So you could have a RAID10 on one, and RAID6 on the other. Then you can assign a volume to one member or the other by RAID type.
The LUN block size is 512byte or newer EQL firmware supports 4K LUN block sizes.
The 64K refers the the NTFS filesystem, NOT the EQL array LUN. The NTFS default is typically 4K or 8K depending on size. At format time you can override that up to 64K.
That 64K NTFS cluster size matches the EQL RAID Stripe size. Since they match the writes will be more efficient. However, if you are not putting a large load on the array, you won't likely see any difference.
Regards,
Don
Sandro Silva Alves
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December 21st, 2018 03:00
Yes, I have only one array with all disks. I mean it's full.
I realize the configuration of the LUN, I can choose the type of RAID. So that means nothing changes for my case, right?
Any LUN will work with the initial setup that is RAID50, right?
Regarding the blocks, yes, I made confusion. Actually I can create from 512bytes or 4k.
But usually 512bytes is used or since there is a 4k option, the best would be to use 4k?
The question of using blocks of 64K in S.O in relation to the amount of load, is there any reference that you use at the time of definition whether or not to use?
But generally everyone uses 4K in S.O, right?
dwilliam62
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December 21st, 2018 06:00
Hello,
Yes an volume with work with RAID50.
Re: 4K vs. 512byte. In the end there is no difference because the EQL hard drives are 512byte not 4K. So you can create a volume that shows each sector as 4K instead of 512byte but it's being translated to 512b in the process of writing to disk. So no advantage there. I see very few people use 4K. Not every OS or filesystem supports it yet.
re: 64K in S.O. No there's no guideline. It's too dependent on the IO pattern and the load. But making it the best practice whenever formatting a volume is good idea.
Re: 4K in S.O. Most people leave it at "auto" so generally 4K or 8K yes.
Regards,
Don