NFS- SAN - FreeBSD

Tue Jul 21 21:58:20 UTC 2009

Grant,

I mean to say that often times external SCSI solutions (direct attached) 
are cheaper and perform better (in terms of I/O) than iSCSI SANs.  
Especially if you're using many disks.  SANs are generally chosen for 
the ability to be split into LUNs for different servers.  Think of it as 
a disk which you can partition and serve out to servers on a 
per-partition basis, over Ethernet.  That's essentially what an iSCSI 
SAN does.  While DAS systems allow the same sort of configuration, they 
don't serve out over Ethernet, only SCSI/SAS.

Since you plan to use NFS to share the files to the other servers, I 
think it may make more sense for you to use a SCSI solution if yo don't 
need the versatility of a SAN.

Of course I know nothing of how you plan to expand this system, but from 
what I understand, with Dell DAS hardware it is possible to connect up 
to 4 different servers to the DAS and expand to up to 6 15 disk 
enclosures.  The MD3000i (iSCSI) expands only to 3.

Another issue is that without compiling in special versions of the iSCSI 
initiator, even in 8.0-BETA2 (which is not production-ready), iSCSI 
performance and reliability are terrible.  There are other versions of 
the code (which I currently use) for the iscsi_initiator kernel module, 
but unless you're comfortable doing that, you may consider DAS in terms 
of ease of implementation and maintenance as well.

Chris

Grant Peel wrote:
> Chris,
>
> I don't know what a direct attached array is.....
>
> What I was just thinking was move all of the servers /home directory 
> to a huge NFS mount.
>
> If you have the time to elaborate fursther, I would apprciate it...
>
> This iSCSI think has me entrigued, but I must admit I know little 
> about it at this point.
>
> -Grant
>
> ----- Original Message ----- From: "Christopher J. Umina" 
> <chris.umina at studsvik.com>
> To: "Grant Peel" <gpeel at thenetnow.com>
> Sent: Monday, July 20, 2009 11:27 PM
> Subject: Re: NFS- SAN - FreeBSD
>
>
>> Grant,
>>
>> I have to ask, is there a reason you're intent on going with a SAN 
>> versus a direct-attached array?
>>
>> Chris
>>
>> Grant Peel wrote:
>>> Thanks for the reply.
>>>
>>> I have not used/investigated the iSCSI thing yet....
>>>
>>> The original question is can I just use an NFS mount to the 
>>> storage's /home partition?
>>>
>>> -Grant
>>>   ----- Original Message -----   From: mojo fms To: Grant Peel Cc: 
>>> freebsd-questions at freebsd.org Sent: Monday, July 20, 2009 4:21 PM
>>>   Subject: Re: NFS- SAN - FreeBSD
>>>
>>>
>>>   You would be better off at least having the SAN on 1gb ethernet or 
>>> even better tripple 1gb (on a 100mb switch should be fine but you 
>>> need failover for higher avaliability) ethernet for latency and 
>>> failover reasons with a hot backup on the network controller.  I 
>>> dont see why you could not do this, its just iscsi connection 
>>> normally so there is not a big issue getting freebsd to connect to 
>>> it.  We run 2 of the 16tb powervault which does pretty well for 
>>> storage, one runs everything and the other is a replicated offsite 
>>> backup.  Performance wise, it really depends on how many servers you 
>>> have pulling data from the SAN and how hard the IO works on the 
>>> current servers.  If you have 100 servers you might push the IO a 
>>> bit but but it should be fine if your not serving more than 2Mb/s 
>>> out to everyone, the servers and disks are going to cache a fair 
>>> amount of always used data.
>>>
>>>
>>>   On Mon, Jul 20, 2009 at 11:52 AM, Grant Peel <gpeel at thenetnow.com> 
>>> wrote:
>>>
>>>     Hi all,
>>>
>>>     I am assuming by the lack of response, my question to too long 
>>> winded, let me re-phrase:
>>>
>>>     What kind of performance might I expect if I load FreeBSD 7.2 on 
>>> a 24 disk, Dell PowerVault when its only mission is to serve as a 
>>> local area storage unit (/home). Obviously, to store all users /home 
>>> data. Throug an NFS connection via fast (100m/b) ethernet. Each 
>>> connecting server (6) contain about 200 domains?
>>>
>>>     -Grant
>>>
>>>     ----- Original Message ----- From: "Grant Peel" 
>>> <gpeel at thenetnow.com>
>>>     To: <freebsd-questions at freebsd.org>
>>>     Sent: Saturday, July 18, 2009 10:35 AM
>>>     Subject: NFS- SAN - FreeBSD
>>>
>>>
>>>
>>>       Hi all,
>>>
>>>       Up to this point, all of our servers are standalone, i.e. all 
>>> services and software required are installed on each local server.
>>>
>>>       Apache, Exim, vm-pop3d, Mysql, etc etc.
>>>
>>>       Each local server is connected to the Inet via a VLAN (WAN), 
>>> to our colo's switch.
>>>
>>>       Each server contains about 300 domains, each domain has its 
>>> own IP.
>>>
>>>       Each sever is also connected to a VLAN (LAN) via the same 
>>> (Dell 48 Port managed switch).
>>>
>>>       We have been considering consolidating all users data from 
>>> each server to a central (local), storage unit.
>>>
>>>       While I do have active nfs's running (for backups etc), on the 
>>> LAN only, I have never attempted to create 1 mass storage unit.
>>>
>>>       So I suppose the questions are:
>>>
>>>       1) Is there any specific hardware that anyone might 
>>> reccommend? I want to stick with FreeBSD as the OS as I am quite 
>>> comfortable admining it,
>>>
>>>       2) Would anyone reccomend NOT using FreeBSD? Why?
>>>
>>>       3) Assuming I am using FreeBSD as the storage systems OS, 
>>> could NFS simply be used?
>>>
>>>       4) Considering out whole Inet traffic runs about 2 Mb/s, is 
>>> there any reason the port to the Storage unit should be more than 
>>> 100 M/b (would it be imparative to use 1 G/b transfer)?
>>>
>>>       TIA,
>>>
>>>       -Grant
>>>
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>>>
>>>
>>>
>>>
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>>>
>>>
>>>
>>>   --   Who knew
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>>
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