iSCSI performance question...

kitt001

Dabbler
Joined
Jun 2, 2017
Messages
29
A SuperMicro 6049P-E1CR36L chassis with an X11DPH-T motherboard and:
  • (2) Xeon 3206R 8-Core CPUs (1.9Ghz, 11MB)
  • 256GB 2933Mhz ECC Memory
  • (2) 256GB Micron SSDs (for the OS)
  • (1) 2TB Intel DC P4511 M.2 PCIe NVMe (for the L2Arc) (has Enhanced Power Loss Data Protection according to Intel's site)
  • (1) 375GB Intel Optane P4801X M.2 PCIe NVMe (for the ZIL/SLOG) (has Enhanced Power Loss Data Protection according to Intel's site)
  • (1) Intel X710-DA2 dual 10Gb/s SFP+ card
  • (20) 6TB SAS 12Gb/s 7200 disks (six 3-way mirrors plus two hot spares)

An alternative would be ...
A SuperMicro 5049P-E1CTR36L chassis with a X11SPH-NCTF motherboard
  • (2) Xeon 4215 8-Core (2.5GHz, 11MB)
  • 512GB 2933Mhz ECC Memory (to offset the absence of L2)
  • (2) 256GB Micron SSDs (for the OS)
  • (1) 375GB Intel Optane P4801X M.2 PCIe NVMe (for the ZIL/SLOG)
  • (1) Intel X710-DA2 dual 10Gb/s SFP+ card (May substitute with (2) 520's if my vendor has them available)
  • (20) 8TB SATA 6Gb/s 7200 disks (still six 3-way mirrors plus two hot spares)
New total (potential) yield would be 24TB (of which, I'd be tempted to provision up to 18-20), but the overall net price increase is only around $500. Does this spec make more sense? 512MB of RAM is the max for this board and it only has one PCIe M2 slot, so if I need to add L2, I'd have to go the pricier add-on card route, or use a SATA SSD.
 

kitt001

Dabbler
Joined
Jun 2, 2017
Messages
29
More information - that I should have thought to gather ahead of time (seems working from home for several months has made my brain numb).
I'm far from an expert on this NAS/SAN, I should have started with what the old system was telling me (beyond that it was reaching it's storage capacity) ... anyway;

I looked closer at the system that I'm replacing and learned a few things, going back a week:
  • Neither of the network interfaces logged a max greater than 1.75Gb/s in or out and both averaged under 50Mb/s.
  • CPU, in it's max usage column logged 94.36% idle (97.22% Avg idle), and load 1/5/15 max at 4.02/1.78/1.24, with a 1 min Avg of .57
  • L2 NVMe logged disk IO max read/write of 15.8Mb/28Mb, Avg read/write 20.9k/57.6k, and total read/write 12GB/33GB over the period
  • The iSCSI target logged a max read/write 239MBps/215.8MBps, and and Avg read/write of 5.7MBps/11.6MBps
  • I also learned that I have no idea what the ZFS ARC graphs are telling me, so I'm not sure what of that information is most telling to understand how much benefit we may realistically be getting from it.
This chassis is running (2) Xeon E5-2609 v4's (1.7 GHz), and 128GB RAM

That box was initially built after some of @jgreco's input (this thread), which was invaluable at the time; and probably a big part of the reason I've never had any complaints about the system until the whole "we're out of space" stuff started. This time, I was just blindly trying to replicate that system on the larger scale, but, I may not need to if the L2 isn't doing a whole lot of contributing here.

What values of the ARC information on the current system teach me the most regarding it's contribution?
 
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