146Gb disks vs 300Gb. 10k vs 15k

[G. Rerink]

Our current eva3k is equipped with only 146Gb disks for Unix. Now we want to use 300Gb disks for the windows environment.
Is performance of the 300Gb disks an issue?
And is it nescesarry to use 15k disks instead of 10k for performance?

[Mark Poeschl_2]

HP Best Practices list a 30-40% improvement in performance for 15K disks over 10K. You might see even worse than that if you went from 146/15K to 300/10K because now more requests are likely to end up on the same (slower) spindle simply because it's larger. The performance degradation will be most noticeable if your workload is lots of small, random I/O requests. Having said that, we use 300G/10K drives on our Windows EVA3K running a fairly active SQL Server database with no issues. So is it "necessary"? No way to tell for sure without a detailed analysis of your workload and a comparison of what your Windows storage is on now vs. the EVA's capability.

[Cass Witkowski]

Are the 300 GB disk SCSI or SATA?

If you are doing a lot of disk I/O and the drives are SATA then you may see more disk failures. From what I recall SCSI disks are designed for 100% duty cycle but SATA drives are designed for 20% - 30% duty cycle.

Using SATA drives for nearline backup is great. Using them for an active database is not a good idea.

[Jefferson Humber]

15K HDD's are much more expensive than the 10K models, and some times it's better to go for the 10k's

For instance what you pay for 20x15K HDD's, may get you 35x10K HDD's in comparison. Having more spindles in your array (although of slower rotational speed), may in fact improve overall performance (and of course give you more usable space).

I have seen some calculations for this somewhere (on a course I think), so it's worth bearing in mind if you have enough free enclosures to house them.

Also it depends on how cheaply you can get the disks for, every supplier is different..... some may have a special offer on though !

[raadek]

Bear in mind that there are some other considerations re 'many 10k drives' vs. 'few 15k drives'.

E.g. limited number of bays in your existing enclosure. Or (maybe even more important) larger number of drives means higher probability of data loss in RAID5 array - a simultaneous failure of two drives is more likely to happen when you have plenty of them.

[Jefferson Humber]

The EVA Best Practices paper gives all the pro's & con's of both approaches;

http://h71028.www7.hp.com/ERC/downloads/4AA0-2787ENW.pdf

[m saravanan]

Rerink..

Reference to EVA Best practices Guide,

Cost/IOPS :
- I would suggest you to use 146 GB 15K rpm disk drives

Performance Wise:
- Also , 15k rpm disk will improve the performance. More than that no. of spindles also decides the performance.

You can find more info. in Best practices guide.

Regds,
Saravanan