Operator asked why not move all 768 GB across. It does not fit the
board's shape: the R640 has 24 slots at 6 channels/socket x 2 DPC, the
R750xa has 16 at 8 channels/socket x 1 DPC.
768 GB is either 24x 32 GB (more DIMMs than slots) or 12x 64 GB (fits,
but populates 6 of 8 channels per socket and gives up ~25% of memory
bandwidth). The board wants 16 identical DIMMs. So the targets are
512 GB if they are 32s, or 1 TB if they are 64s — taking 12 from one
spare and 4 from the other. In the 64 GB case the answer beats the
question.
Also recorded: beyond ~512 GB the return is marginal for this workload,
so take 1 TB because it is free rather than because it is needed; 64 GB
LRDIMMs run ~50 W hotter in a chassis whose high-performance fans are
unaccounted for on the invoice; and DIMM slot count now needs to be on
the iDRAC pull, since the 16-slot figure is inferred from the factory
CSV and is load-bearing for a 512-vs-1024 decision.
Memory-only; no version bump per the SemVer SKIP list.
Operator has 2x Dell R640 at 768 GB each and asked whether the memory is
interchangeable with the R750xa. Both are DDR4 RDIMM platforms and Dell
does not vendor-lock DIMMs, so the answer is very likely yes.
- 16 slots in the R750xa x 32 GB = 512 GB, double the factory spec, and
it deletes the 8x M04W6 purchase.
- Gating question is RDIMM vs LRDIMM. 24x 32 GB 2Rx4 RDIMM is the safe
and most likely case; 12x 64 GB LRDIMM needs Ice Lake support checked.
- Cleanest harvest is to strip one R640 entirely and leave the other
whole, rather than half-emptying both into unbalanced populations.
Separately, reading the factory CSV to answer this surfaced a gap in the
diff table: the reseller also swapped 2x Xeon Platinum 8362 (32C/64T,
265 W, DDR4-3200) for 2x Xeon Silver 4314 (16C/32T, 135 W, DDR4-2666).
The Silvers were recorded under "As bought" but never diffed, so the swap
went unremarked. Two consequences: the box cannot use the 3200 rating the
buy list was paying for, which makes 2666 R640 DIMMs a free lunch; and
the CPUs draw 260 W less, which the existing ~1,020 W power figure
already assumed correctly.
Memory-only; no version bump per the SemVer SKIP list.
comfy-dev's disk-vs-catalog diff and a recount of my own figures both
landed on this thread. Two numbers were wrong and both were headed for
the operator's sizing conversation.
- My ~90% was a double-count. I read ALLOC 1.45T while their pull was
running and then added the full ~112 GB on top; most of it was already
in that reading. "Onboarded" is not "landed". Settled payload is
~1.47 TiB and the as-bought mirror lands at 84%, not 90%.
- comfy-dev's "pruning gets us nearer 45%" is the striped figure. On the
as-bought pair mirrored, deleting all ~215 GiB of unreferenced weights
still lands at 72%, with ~140 GiB of runway on a store that took on
~100 GiB in one day. The constraint is vdev layout, not payload — a
1.75 TiB pool stays 1.75 TiB whatever goes in it.
- So the prune audit and the drive purchase are independent decisions
and neither gates the cutover. Presenting them to the operator that
way rather than as a trade.
Also recorded: pool arithmetic (1.75 / 3.49 / 3.57 TiB), the mirror-vdev
smallest-member gotcha if the new drives get paired one-each with the
1.92s, comfy-dev's 34 GiB of uncatalogued LTX 2.5, and an open question
back to them on whether the H3 encoder's nvfp4 pin was set under a
Blackwell assumption that sm_89 does not satisfy.
Memory-only; no version bump per the SemVer SKIP list.
Measured irv-ml1's storetank against the R750xa's as-bought drives while
answering comfy-dev's "does the Ada box have ZFS?" question.
- storetank: 1.81 TiB pool, 1.45 TiB used, 80% CAP already, compression
off at compressratio 1.00x (safetensors incompressible — no win at
recv). comfy-dev's ~112 GB batch is landing into it now.
- The R750xa shipped 2x 1.92 TB SATA SSD; mirrored that is ~1.74 TiB,
smaller than the pool it receives from. Migration would arrive at
~90% full with no growth room.
- Buy list: +2x 2 TB SATA SSD (6 bays free, HBA355i has the ports) ->
two mirror vdevs striped, ~3.49 TiB at ~45%, redundancy intact.
- Retain vs reclaim irv-ml1's /storetank after cutover: RETAIN
recommended, surfaced to the operator.
Also corrects branch (b)'s recorded rationale. comfy-dev enumerated all
twelve running containers: only comfyui mounts /storetank, so (b) was
unavailable during the transition, not structurally. Right conclusion,
wrong reason — infra-ops reasoned about the box when the question was
about the mount.
Memory-only; no version bump per the SemVer SKIP list.
Dell R750xa JPJ1ZP3, 2x RTX 6000 Ada to be fitted, ComfyUI's new home at NH3. Diffing
Dell's factory CSV against the reseller invoice shows four downgrades: half the RAM, the
2400 W PSUs, and the GPU risers, cables and high-performance fans all absent.
Records the resolved GPU power chain, correcting my own first answer: the chassis' CPU
8-pin cabling is the right source type and NVIDIA 930-00030-1546-000 bridges it to the
card's 12VHPWR, so the PCIe-type RCCWC I first proposed is withdrawn. Also closes the NVMe
question — the backplane is SAS/SATA only — and notes that free PCIe slots may moot it.
Auto-archival fired at 308 lines; seven entries moved to archival-memory.md. The 250-line
target was not reached because the guards hold nearly everything else back as under 14 days
or carrying open deferred work.
vh