Running StarWind on W2K8 R2 Web Edition

[alozzy]

Hi,

I notice in the system requirements for StarWind SAN the following comment:

It is not recommended to install StarWind on Windows Storage server or Web server editions.

Why is that? As a purpose built storage appliance, I would have no need for services that would require Windows user or device CALs.

A technical discussion of the reasoning for why W2K8 R2 Web Edition is NOT recommended would be appreciated...

Thanks!

[anton (staff)]

Running iSCSI services on something located inside DMZ (read on the gate between Internet and Intratet) opens a huge security hole we don't want to be responsible for.

Hi,

I notice in the system requirements for StarWind SAN the following comment:

It is not recommended to install StarWind on Windows Storage server or Web server editions.

Why is that? As a purpose built storage appliance, I would have no need for services that would require Windows user or device CALs.

A technical discussion of the reasoning for why W2K8 R2 Web Edition is NOT recommended would be appreciated...

Thanks!

[alozzy]

Hi Anton,

I wasn't suggesting that the server be placed in a DMZ segment! I'd never do that. If I were to build a SAN, it would only ever be connected to an isolated LAN dedicated to iSCSI traffic.

I'm just wondering why the base Windows OS can't be the web edition. Also, why not Windows Storage Server 2008 (32 bit)? I'd like to deploy StarWind on a Dell PowerVault NX3000, which already has Windows Storage Server 2008 preinstalled. Although I could purchase a new license of Windows Server 2008 R2, I'd prefer to avoid the additional expense if possible.

Please provide a technical discussion of why Windows Storage Server 2008 and Windows Server 2008 R2 Web edition are not recommended. I realize a 32-bit OS can only address 4GB of RAM per process (2GB user mode, 2GB kernel mode), but can Starwind SAN run multiple processes of itself in order to use more than 2GB of RAM for caching on 32-bit operating systems?

Thanks!

Alan

[anton (staff)]

StarWind *CAN* run on Web edition but in most cases it would be used to serve http load to "outside" so it's begging for troubles.

StarWind *CAN* run on WSS but in most cases vendors so save on CPUs and available RAM shipping very weak configs we don't shine on.

Assuming 1) and 2) we've restricted production use to avoid Web edition and WSS. But we'll flex out requirements referencing what's in 1) and 2)

P.S. StarWind uses AWE so *CAN* address more then 2GB of RAM for cache under 32-bit OSes.

Hi Anton,

I wasn't suggesting that the server be placed in a DMZ segment! I'd never do that. If I were to build a SAN, it would only ever be connected to an isolated LAN dedicated to iSCSI traffic.

I'm just wondering why the base Windows OS can't be the web edition. Also, why not Windows Storage Server 2008 (32 bit)? I'd like to deploy StarWind on a Dell PowerVault NX3000, which already has Windows Storage Server 2008 preinstalled. Although I could purchase a new license of Windows Server 2008 R2, I'd prefer to avoid the additional expense if possible.

Please provide a technical discussion of why Windows Storage Server 2008 and Windows Server 2008 R2 Web edition are not recommended. I realize a 32-bit OS can only address 4GB of RAM per process (2GB user mode, 2GB kernel mode), but can Starwind SAN run multiple processes of itself in order to use more than 2GB of RAM for caching on 32-bit operating systems?

Thanks!

Alan

[alozzy]

Hi Anton,

Thanks for the explanations...

Currently, we have a Dell PowerVault NX3000 (single Xeon L5520 CPU, 3 GB DDR3 RAM, PERC 6i RAID cntrl) with (4) 2 TB SATA drives in a RAID-5 configuration that are carved up for the iSCSI LUNs (OS is on a separate 2 drive RAID-1). The server has Windows Storage Server 2008 Standard (64-bit) preinstalled and to date we've been using the Microsoft iSCSI software target with "acceptable" performance (not great, just OK). Sorry about the mixup on 32-bit OS - I just checked today and was delighted to see that it's 64-bit.

I'd like to upgrade to the following setup:

- Dell PowerVault NX3000 will be repurposed to use (6) 2 TB SATA drives in a RAID-10 configuration. Will likely bump up RAM to 8 GB to optimize write-through caching (I won't use write-back on a single server, too risky. Also, RAID controller does have battery backed write-back caching enabled)
- The existing Windows Storage Server 2008 (64-bit) OS will be kept as is, except that we will decommission the MS iSCSI software target
- StarWind iSCSI SAN CDP Edition will be deployed

Can you confirm that the above would be supported?

Questions:

• what RAID segment size should I use for optimal performance?

• What default allocation unit for the NTFS volume where the StarWind image file(s) would reside?

• Will Windows automatically align the NTFS partitions with the RAID 10 array boundaries?

• Any suggestions on the VMFS volumes?

• What StarWind configuration would you recommend?

The iSCSI target will be access by (2) VMware ESXi 4.1 U1 servers running approximately (20) VMs. Almost all VMs have low IOPS and throughput requirements. There will likely be (3) 2 TB LUNs exposed by the StarWind iSCSI target, unless you suggest otherwise.

I'm thinking that with an underlying RAID-10 array and the introduction of read caching by StarWind SAN, performance should improve considerably. I don't need to knock it out of the park on the performance front, it would just be a nice bonus to improve things...

I'm happy to work through your sales channel if that's preferred but from my perspective, when I can pose these questions to the CTO I'm a happy guy

Thanks!

Alan

[alozzy]

Hi Anton,

I'm hoping to begin testing with StarWind target this week. I've got the hardware ready to go.

Whenever you have a chance, please comment on the questions in my last post...

Thanks,

Alan

[Max (staff)]

Hi Alozzy,
The upgraded configuration looks good, just make sure there is no teaming on the network side.

what RAID segment size should I use for optimal performance?

>>>I would go with 64K, this way you align your iSCSI block size with RAID block size.

What default allocation unit for the NTFS volume where the StarWind image file(s) would reside?

>>> 64 is the recommendation here as well

Will Windows automatically align the NTFS partitions with the RAID 10 array boundaries?

>>>Yes, if you're initializing as GPT

Any suggestions on the VMFS volumes?

>>> Not much, just follow VMware's iSCSI best practices and you should be fine.

What StarWind configuration would you recommend?

>>> Based on the fact that you only have one StarWind box, there's not much I can recommend. It is a good idea to add a UPS to the server.
Also, keep your networking redundant, so if a network switch fails your VMs don't loose any data.

[alozzy]

Hi,

The Dell Perc 6i controller on the PowerVault NX3000 provides an advanced option for setting the stripe size of the RAID-10 array. However, the setting is actually labeled "Stripe Element Size" (which is 64K by default) and the description in the manual reads:

Stripe Element Size specifies the size of the segments written to each physical disk in a RAID 0, 1, 5, 6, 10, and 50 virtual disk

When I asked one of your sales engineers about segment vs stripe size, he stated:

I’m referring to the stripe size and not the segment size. You should set the stripe size to 64k. I would assume the RAID CTRL setting “stripe element size” is referring to stripe size, but I would suggest checking the manufacturer’s documentation just to be sure

So, that implies that I need to adjust the "stripe element size" parameter so that the "full" stripe size (across all disks) equals 64K? If so, since RAID-10 is a nested RAID group (a RAID-0 array of mirror drives) and I've got a (6) drive RAID-10, then the "stripe element size" parameter would have to be set to a non-integer since the RAID-0 stripe is across (3) sets of RAID-1 pairs (64K / 3 = 21.333K)?!

Either your sales engineer is wrong (and the 64K suggested value refers to the segment size and not the stripe size), Dell's definition is wrong, or I've misunderstood something...

Can you explain the discrepancy?

I'd really like to get started with the trial version as I'm going to purchase soon, provided the testing goes well. However, I first need to understand how to optimally configure the Perc 6i controller...

Thanks!

Alan

[jeddyatcc]

I think we are having a bit of a word game here. What I understand of Stripe Size in a RAID 10 array (assuming 64k strip size) is that each RAID 1 has a 64k stripe and the overlying RAID 0 has a 64k stripe. Stripe size to me means the RAID controller writes/reads 64k of information to a disk before moving on to the the next disk in the array. I honestly have no idea if "Stripe Element Size" equals RAID strip size, and would recommend upgrading firmware/confirming with DELL what that actually means, looking at the manuals definition I would say that strip element size and stripe size are equivalent. Performance wise I have not noticed a huge difference based on format/cluster or stripe size, but every setup is different.

[alozzy]

Hi,

Agreed, there's a problem with the definition of RAID "stripe size" and it seems to be industry wide, with conflicting definitions for "stripe size" muddying the waters. Pretty confusing as an end user.

All that really matters to me is that I get the correct value for "stripe element size" so that everything is optimal with the higher storage layers (including StarWind).

Based on your definition, I can use the PERC 6i controller default value for "stripe element size" (which is 64K). Correct?

Thanks!

Alan

[jeddyatcc]

I would certainly do that and run some tests, then I would set it larger and try again, then smaller. Yes it is kind of tedious, but each RAID system functions differently. On my DELL boxes of SATA drives, I get better performance at 32k stripe, but 64k or 4k format. It all depends. I spent 2-3 weeks testing just that, before I implemented it in production. I would definitely start off at 64k all the way through and only start making adjustments if you feel you need more speed. I wanted to get as much as I could and most of these adjustments are only 1-2%...

[anton (staff)]

I would suggest to test using something being close to your primary workload For a pure synchetic stuff should be 4KB, 8KB and 64KB, 100% read, 100% read and 50/50 split. Just my $0.02

I would certainly do that and run some tests, then I would set it larger and try again, then smaller. Yes it is kind of tedious, but each RAID system functions differently. On my DELL boxes of SATA drives, I get better performance at 32k stripe, but 64k or 4k format. It all depends. I spent 2-3 weeks testing just that, before I implemented it in production. I would definitely start off at 64k all the way through and only start making adjustments if you feel you need more speed. I wanted to get as much as I could and most of these adjustments are only 1-2%...