Unsolved
This post is more than 5 years old
5 Posts
0
396
May 8th, 2014 03:00
VNX 5300 RAID Query
Heylo,
We are implementing VNX 5300 block with 8 SAS 600 GB disk and 112 NL-SAS 3 TB disk for our CCTV project.
As per the best best practice we need to have 4 Hot spare and we will be left out with 108 NL-SAS drives,
If we create RAID-6(14+2) we will use 6 X 16=96 disk and left out with 12 disk.
Should i create RAID 6 with 10+2 on this ?
Normally What would be the best practice for this type of configuration regarding the storage pools ?
Should i put all the 112 disk in one pool or i should limit 40 disk in one pool ?
Thanks in Advance
Muhammed Basheer MP
No Events found!
ZaphodB
195 Posts
0
May 9th, 2014 15:00
I have seven similar systems at work which are used with VMWare. But I ordered them all with a vault pack that matched the rest of the disks (some are 120 x 2TB disks and some are 120 x 3TB disks). In those cases I used to make 7 x (14+2R6), but I have shifted them all to 8 x (12+2R6). I get a little less net usable capacity, but we do not allocate 100% of the space anyway, and the symmetry and modestly smaller RAID group sizes help with other things. Both of those configurations 'consume' 112 disks and leave me the four spares you are looking for.
When carving 5300s into pools I tend to make three pools of similar resources. For large NL-SAS disks pools want to use either 6+2R6, or 14+2R6, and I would strongly recommend against mixing array sizes within a single pool. If you are looking for streaming performance I would suggest caution with regard to using thin pooled LUNs. As they grow they become somewhat disorganized, and their sequential performance tends to degrade.
What sort of a balance are you looking for between capacity and performance? What LUN sizes are you looking to serve to the video servers?
Your maximum capacity would come from defining either (6 x 14+2R6) + (1 x 10+2R6), or (5 x 14+2R6) + (2 x 12+2R6); either of those yields 94 disks of available net capacity.
I am going to mention something a bit outside the box that I do with all of my straight NL-SAS units. A 5300 with advanced functions enabled on it only has just under 2GB of available RAM for read and write cache. It doesn't take too much activity to drive the SPs to a state where they continuously force-flush writes. When that happens, their read and write performance becomes ...erratic... For units without mixed disks I remove the enablers for advanced functions. With those stripped out the available RAM for cache use doubles. The available memory on my 'plain' units is 3997MB, and they are stable and robust.