Would PCI HBA card allow Dell T7500 to work with larger HDs?

[jerkbag]

Hi All,

I have a Dell T7500 that's been a rock-solid Truenas since the 9.x days (recently I virtualized it through ESXI). I have 4 X 2TB Drives in a RAIDZ1 pool. Been on my list for awhile to get some more space, and it's been so long enough since I looked at HDs that I was shocked to see 16 and 18TB drives for almost the same price I paid for the 2TBs years ago! I was thinking of moving to a 2 X 16-18TB drives in a mirror.

The issue is the Dell T7500 is limited to 2TB drive size. I don't 100% understand where the limitation lies -- is this something I could overcome using an a PCI HBA card instead of the onboard SATA ports? And if so, which would be appropiate? Or is the drive size limiting tied to the CPU or other inner workings that can't be altered?

And assuming I could get this to work -- any concerns with two big drives in a mirror? Seems safe enough to me? I know RAIDZ1 should be avoided with larger drives. Also: I currently give the TrueNas VM 8GB ram -- would it really be necessary to give it 16GB if I upped the pool size? I've seen 1GB per TB recommended, but is that simply for peak performance, or to avoid issues? No jails or docker or anything on the Truenas just storage being shared back to other VMs.

Appreciate the help!

 

[artlessknave]

I know RAIDZ1 should be avoided with larger drives.

raidz1 on drives larger than 2TB is violently discouraged.

Dell T7500

as these products can be fairly differently configured, just putting a model number is insufficient for the forum requirement of including your hardware in a post. not only does it mean we have to use our time to go look it up, but when we look it up all we see is a range of configs, not YOUR config. you likely understand what you have better than we do, so its best to just state it.
also very important is this line "TrueNas VM 8GB ram"; how are you virtualizing it? did you pass the HBA through to truenas? which hypervisor?

I currently give the TrueNas VM 8GB ram -- would it really be necessary to give it 16GB if I upped the pool size?

this is the absolute minimum to install truenas. your question is like asking "I can put a trailer hitch on a smart car; that should be enough to pull a 10 person camper right?"
so the answer is 'yes'. you need to give it more RAM. 16GB is the realistic minimum; pretend the 8GB number doesn't even exist.

truenas and zfs will use RAM if it needs to repair the pool from something going really wrong. if there is not enough RAM to do this, the pool will be impossible to import until you get more RAM.
by default truenas adds some swap space to all data disks; this enables it to swap in these cases instead of just being unable to import....but if it has to swap to import, your import is going to be measured in days to weeks.
additionally, more RAM will always = better performance.

The issue is the Dell T7500 is limited to 2TB drive size. I don't 100% understand where the limitation lies -- is this something I could overcome using an a PCI HBA card instead of the onboard SATA ports? And if so, which would be appropiate? Or is the drive size limiting tied to the CPU or other inner workings that can't be altered?

now, onto your main question: a SAS HBA (PCIe, not PCI, as these are different) will give you 8 direct connect drives, or up to 256 drives with expanders. popular ones are LSI 2008/2308 for SAS2, with sas3 available but massive overkill for spinners.

"
Integrated LSI 1068e SAS/SATA 3.0GB/s controller supports host-based RAID 0 or 1. Optional PERC 6/i PCIe SAS/SATA/SSD hardware RAID card
supports RAID 0, 1, 5, 10"

https://i.dell.com/sites/doccontent/shared-content/data-sheets/en/Documents/dell_precision_t7500_specsheet.pdf

it looks like this model only comes with SAS1 HBA (LSI 1068e) or a SAS1 RAID (PERC 6/i), so that would be the limitation. while the SAS1 spec can handle larger than 2TB, a lof of the hardware was designed in a way that it can't actually do so. it looks like you should have 2x PCIe x16 slots? if so, any of them can run an HBA for you.

what I can find for the 1068e tells me you might have a regular PCIe card one; if you so, a SAS2 HBA should be a drop in replacement.

if you have the RAID card that should be replaced ASAP anyway; unfortunately, that would be an integrated and might not be replaceable, per se. some of them sit in a pcie slot, while others have proprietary slots.

this hardware is on the very old side; i would seriously consider planning a replacement.

 

[jerkbag]

as these products can be fairly differently configured, just putting a model number is insufficient for the forum requirement of including your hardware in a post. not only does it mean we have to use our time to go look it up, but when we look it up all we see is a range of configs, not YOUR config. you likely understand what you have better than we do, so its best to just state it.
also very important is this line "TrueNas VM 8GB ram"; how are you virtualizing it? did you pass the HBA through to truenas? which hypervisor?

Sorry about that! Appreciate you taking the time without having all the info. The Dell has an integrated LSI controller that I am passing thru to a TrueNas VM, using Vmware ESXI.

it looks like this model only comes with SAS1 HBA (LSI 1068e) or a SAS1 RAID (PERC 6/i), so that would be the limitation. while the SAS1 spec can handle larger than 2TB, a lof of the hardware was designed in a way that it can't actually do so. it looks like you should have 2x PCIe x16 slots? if so, any of them can run an HBA for you.

Thanks this is what I was hoping -- that a new controller would bypass the 2TB drive limit.

 

[artlessknave]

you need to check if its the HBA or the perc; this is genuinely important.
raid cards often add junk to disks, and if you built with that the disk will not work with anything but another perc.