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ESXi and cheap RAID card?

Hi all,

I have a whitebox home lab computer. I've been slowly learning about VM's and ESXi. I'm now trying to learn the disk system aspects.

From what I've gathered, you can run about 3 or 4 VM's in an ESXi box before you start suffering from disk i/o bottlenecks. I understand that you can alleviate this by buying a card with "write-through" capabilities. But then there are things like battery backups to think about, etc.

Given my home lab budget, i may have to buy something on fleabay. Can someone recommend a *specific* card model, along with any specific features to look for (battery backup), etc.?

Thanks in advance.
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Go-Bruins
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Go-Bruins
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
What is your budget ?

HP Smart Array Controllers
LSI SATA/SAS controllers - LSI 9211-8i
IBM Controllers

Have you considered if this is just for Lab, using VMware Workstation, and created ESXi servers as VMs ?

see my EE Article

HOW TO: Set up a lab environment for vSAN using VMware Workstation
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Go-BruinsAuthor Commented:
Thanks for the reply.

I'd like to stay under $150 if possible.

The LSI 9211-8i is one of the ones i looked at, but it doesn't appear to have the battery backup, unless i'm missing something.

The research I did on the IBM cards led me to the M1015 card, but it doesn't appear to have a battery either.

I'd like to set up a separate and distinct machine for testing, even if it's a home lab.
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Go-BruinsAuthor Commented:
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Yes, M1015 will also work.

From what I've gathered, you can run about 3 or 4 VM's in an ESXi box before you start suffering from disk i/o bottlenecks. I understand that you can alleviate this by buying a card with "write-through" capabilities. But then there are things like battery backups to think about, etc.

I'm afraid what you pay is what you get, as you pay more for a card with Battery Backup, or Battery Backup Write Cache controller, e.g. BBWC, you will pay more for the card.

But how many disks, will you also be using and will these be SAS or SATA, SATA disks have very low IOPS, also RAID type will make a big difference, e.g. RAID 10 for performance.

and with low cost SSDs, you may get better performance just using SSDs for a LAB.

so it's not just about the card, it's how it's used, with what, how many disks, of type, and RAID configuration.
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Go-BruinsAuthor Commented:
The home lab is a white box with 32 GB RAM. There are four VM's (with no more planned), but they are on independent SATA disks.

Will a RAID card really show great gains given the above scenario?
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
how many disks in RAID ? 4,,8,10

what RAID type ? 0,1, 10, 5, 6

what type of SATA disks ? 7k, 10k, 15k

Total number of IOPS per SATA disk is about 40-70
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Go-BruinsAuthor Commented:
I have one SSD, and a couple of WD enterprise 7K drives.

None of them are in RAID. They are all standalone.
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
2 SATA disks ? and you want to RAID them ?
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Go-BruinsAuthor Commented:
HI, no I'm not interested in RAID at all. I was just wondering if an aftermarket card would up the throughput even without RAID.
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
To increase throughout, you need to use more disks, RAID them, and use RAID controller with BBWC.

at present, you are just using single disks, as a datastore.

if we say, that maximum IOPS per disk is 70 (SATA), so that's 70 per Datastore

combine them in a RAID configuration, two disks, RAID 1

that's about 90 IOPS per entire datastore....

use 4 disks - RAID 10

180 IOPS

use 4 disks - RAID 6

80 IOPS.

So just purchasing a new storage controller, is not going to do what you want.

Use more SSDs, or more disks, in a RAID configuration.

and at present, a disk failure, and you'll lose all your VMs.
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Go-BruinsAuthor Commented:
Ok, thank you.

I was under the false impression that a RAID card would help significantly with i/o even under my setup.
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
not with two disks.
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