Indexers mixed with sas-2 and sas-3

[matthewssa]

Good day,

I am managing an infrastructure that currently has both sas-2 and sas-3 hard drives mixed in with the OS and Data partitions on the indexers. I was curious if this would have an impact across all of the other indexers since sas-2 operates at 6gbps vs sas-3 that operates at 12-gbps.

If I remember correctly indexers utilize the member with the lowest CPU and memory. Would this happen for sas speeds too?

[PickleRick]

There's no simple dependency between disk bus speed and the overall disk subsystem performance.

I assume you're not using single disks but rather RAID-1 or 10 arrays. In this case OS-level buffering/caching as well as the array controller level caching/buffering affect the overall system performance (as well as other parameters like stripe size, block size, filesystem parameters and so on).

So I can imagine a SAS-2 based system running much "better" than SAS-3 based and vice versa.

Additionally, SAS-2 vs. SAS-3 mostly influences continuous transfers. With random seeks (that's where IOPS count the most) it's also how the OS queues and optimizes the read/write requests and how the array controller and the drive itself does it.

So it's not that easy.

[gcusello]

Hi @matthewssa,

my first hint is to check the performances of your sas disks: Splunk requires at least 800 IOPS (better 1200), how many IOPS have your disks?

This is very relevant if you're using them for hot and warm buckets, less relevant if you're using them for cold buckets.

Ciao.

Giuseppe

[isoutamo]

Hi

as @gcusello said, it's more important how much IOPS your disks can deliver than what is connection type for those. Basically you could mix those without issues if all those are capable for min 800 (preferred 1200+) IOPS.

r. Ismo