2010-09-06 10:24 PM
I've heard lots about fibre channel disk is for apps that require high IO and SATA is good for things like file data. What recommendations can you give for which type of disk an app should sit on?
From my thinking disk are aggregated together providing a pool of IO, if the app profile fits within the aggregated IO, does it matter whether the disk is aggregate is made up of SATA or fibre channel disks?
2010-09-07 05:25 AM
A single SATA disk can do about 75 IOPS and a single FC disk 150 IOPS.
For random type IO, these numbers matter and you need twice the number of SATA spindles compared to FC disks to satisfy a certain random IO load. For sequential IO, there's much less of a difference because SATA disks can handle sequential IO quite well.
This is the reason why FC/SAS disks are recommended for apps like databases that generate lots of random IO. File storage (especially for large files) is more likely to be sequential IO and SATA will be ok for this.
All of this is true for medium work loads. However, if the work load is much too high for the aggregate to handle, we have the impression that FC disks can handle the "overload" better than SATA disks, providing a kind of "graceful performance degradation".
2010-09-07 05:53 AM
I agree with Karl. I just want to add 1 thing: SATA in combination with flash memory (flexscale (PAM II)) and 64 bit aggregates in ONTAP 8.0, I'm sure that you can run more than 90% on SATA. We have several databases and VMWare running on SATA with PAMII. Very nice performance.
2010-09-07 06:52 AM
SATA in combination with flash memory (flexscale (PAM II)) and 64 bit aggregates in ONTAP 8.0
One, tiny comment from me:
Actually 8.0.1 is required as 8.0 doesn't support PAM II (only PAM I).
2010-09-10 01:38 AM
That's great vinformation guys, thanks.
I'm looking to purchase lots of SATA disks to satisfy the performance requirements of some shares. Is there a way to tell if PAM cards would be an effective replacement to purchasing additonal SATA disk?