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Redundant iSCSI SAN

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-Dragon-

2[H]4U
Joined
Apr 6, 2007
Messages
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I'm trying to setup some iSCSI target VMs to provide redundant storage to run other VMs off of in a cluster. So far I've come up with this which will probably work just fine I'm just not sure what the end hardware requirements would be (mostly in memory since thats the only place I'm a bit cramped)

Any other options I'm missing? FreeNAS doesn't seem to support multiple server redundancy easily if at all and I'm not interested in ZFS at all due to the overhead.

Are there any other (free) options I'm missing? This is for a home system so the amount I'd be willing to spend on software for this wouldn't really come close to a real "enterprise" solution.
 
Perhaps he means the additional code necessary to read/write to the drives?

I've never heard of ZFS having much, if any overhead though.
 
RAM overhead, these boxes are a little memory constrained

I don't want to use ZFS lets just leave it at that
 
That link you pointed to looks great, that would probably work well for you.
It makes a good read for anyone else.
 
-Dragon- said:
RAM overhead, these boxes are a little memory constrained

I don't want to use ZFS lets just leave it at that
Click to expand...

it is not uncommon to have people making decisions based on reasons which are misinformed (ex: that zfs has to be ram-hungry.) you seem to have made up your mind, though.
 
Well he wants to do what he wants to do, so we can help him with that.

I do know that for very large ZFS arrays, 4GB+ RAM is necessary, but it's very rare from what I've heard.
 
http://doc.freenas.org/index.php/Hardware_Requirements

RAM

The best way to get the most out of your FreeNAS™ hardware is to install as much RAM as possible. If your RAM is limited, consider using UFS until you can afford better hardware. ZFS typically requires a minimum of 6 GB of RAM in order to provide good performance; in practical terms (what you can actually install), this means that the minimum is really 8 GB. The more RAM, the better the performance, and the Forums provide anecdotal evidence from users on how much performance is gained by adding more RAM. For systems with large disk capacity (greater than 6 TB), a general rule of thumb is 1GB of RAM for every 1TB of storage.

NOTE: by default, ZFS disables pre-fetching for systems containing less than 4 GB of RAM which can really slow down performance. While 4 GB is the listed minimum for pre-fetching to be enabled, the operating system itself resides in RAM. This means that the practical pre-fetching threshhold is 6 GB.

If you are installing FreeNAS™ on a headless system, disable the shared memory settings for the videocard in the BIOS.
Click to expand...
I don't want to dedicate 25-50% of my available RAM to ZFS as I'm not trying to setup a NAS solution I'm trying to setup a VM cluster with redundant storage, that doesn't seem very misinformed to me, I've got a great RAID setup, and all I need is like 2TB total

Anyway, back to the topic on hand which is redundant SANs, anybody who's not a zfs (which isn't a redundant SAN solution anyway just a block storage device) evangelist have something to input on the matter?
 
Actually that 1gb/tb of storage isn't really correct. That is only if you plan on running deduplication to hold the dedup tables. .. I've seen some very well performing zfs setups with 4gb total ram. Will ZFS use every big of ram you throw at it ? Yes, but so will any other decent data store. .. Now, given what you're asking - there is a zfs backed end solution that can be made auto-failover (Nexenta Enterprise with HA cluster plug in - but is /is/ commercial. There are also /many/ redundant SAN possibilities out there, but again all commercial.

If you want to cobble together a free one, well the freenas you mention above might be the only one.
 
Just buy this! You will be fine!

http://cgi.ebay.com/Used-3Par-Data-...906?pt=LH_DefaultDomain_0&hash=item587d3459ca

In all seriousness. Openfiler has a HA/Clustered ability with heartbeat. It can be redundant and offers ISCSI and can interoperate with fiberchannel hardware. It is linux based though. And getting HA/DRBD to work is a bitch.

Also if you want to buy a badass and totally affordable boxed solution:

http://www.qnap.com/USEng/pro_detail_feature.asp?p_id=184

Really all of their products are 100% vmware certified, offers clustered ISCSI so many initiators can use the same target and lun. Also it supports built in easy mode device to device redundancy. So what happens on NAS/SAN 1 it copies in real time to NAS/SAN 2. And the prices are great for SMB/Enterprise.

I just ordered the Small Business TS0659 Pro II for about $1250 shipped for my home use. I also run VM's as well but I run them right here on my signature machine as well as my non signature 2500K through iSCSI Targets. I cant wait on this little server. You can even download and install PS3 server lol. I was like SOLD! Much better than my Openfiler NAS I sold already.
 
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Yes, not trying to push zfs down the OP's throat, but others may read this thread, and I see this misinformation all over the place. ZFS does NOT require a ton of ram. For dedup, yes. Also, it WILL use whatever you give it for a read cache, but it's not a prerequisite.
 
I'm using HP's lefthand P4000 units at work, they work amazing for VMware and are fully redundant, have various network RAID levels, etc.

$15000 per ... 3.6? TB for 15k drives, or something like 8TB for 7200RPM drives. Min 2 units of same type.

I'm sure you can do it cheaper, but the interface, expand-ability and reliability of these make them priceless in my opinion.
 
hotcrandel said:
I'm using HP's lefthand P4000 units at work, they work amazing for VMware and are fully redundant, have various network RAID levels, etc.

$15000 per ... 3.6? TB for 15k drives, or something like 8TB for 7200RPM drives. Min 2 units of same type.

I'm sure you can do it cheaper, but the interface, expand-ability and reliability of these make them priceless in my opinion.
Click to expand...

Thats pretty funny. The OP wants a "free" solution and this is for what - a 20-30K solution. . . :). Might as well recommend EMC at that point. . .
 
Guess I thought the clustering thing in OpenFiler was a paid thing but I found this how-to so that might work after all...
 
-Dragon- said:
Guess I thought the clustering thing in OpenFiler was a paid thing but I found this how-to so that might work after all...
Click to expand...

Been there done it, Its a BITCH!!!!

Fair warning. But it worked but not completely using those instructions.
 
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