Thoughts on xServe RAID replacement?

[Alex Gerulaitis]

If I am not mistaken Drobo 800i and 1200i are iSCSI units (not NAS) so they still need to go through a server of sort – will that be xServe via one or more GbE links?

What kind of aggregate bandwidth does the replacement solution need to have? How about expandability?

Drobo units are cool in terms of usability and management. I like the 1200i especially for things like tiering, dual PSUs, swappable I/O module (10GbE in the future perhaps?), mostly tool-less servicing.

Not so sure about performance – it hasn’t been Drobo’s strong point in the past, but have changed to the better since.

If you need iSCSI for some reason, then short of going with much more expensive iSCSI units from the big boys (Dell EqualLogic, HP, EMC, etc.), or using a custom-built one with MS or Linux Storage Servers (which usually requires decent IT VAR support), Drobo units might just be the best choices for iSCSI SAN.

A cost-effective alternative to either iSCSI Drobo or a Fiber Channel unit like the VTrak E-class, is a DAS unit: drop a RAID controller such as ATTO R680 or Areca 1882x into the server, connect a 16-bay SAS expander unit, and that will cost around $3K before you add drives. Really fast, really expandable, highly customizable.

Alex Gerulaitis
Systems Integrator
DV411 – Los Angeles, CA

[Alex Gerulaitis]

[Alex Gerulaitis] “Not so sure about performance – it hasn’t been Drobo’s strong point in the past, but have changed to the better since.”

Just found out Drobo iSCSI units don’t support load balancing (aka bonding, teaming) on their I/O ports so you’ll be limited to line speed of about 120MB/s or less for each iSCSI target. For your client’s 40 users, it’s on the low side even if it’s a low traffic environment.

(I do realize the bottleneck is also on the server – with xServe’s one or two GbE ports, there isn’t much to work with. That however can be changed by upgrading to a different server or dropping a 10GbE card into it. After that, the storage solution better not be the bottleneck.)

Would the DAS (SAS RAID HBA + SAS Expander box + drives) solution I mentioned work for your client?

If not, I’d look for either an iSCSI box that is faster than Drobo, or a Fibre Channel box like the VTrak E-class unit you mentioned, since it can potentially scale to dual 8Gbs channels to the server.

Alex Gerulaitis
Systems Integrator
DV411 – Los Angeles, CA

[Craig Wolf]

Alex.

Thanks for the responses. Sorry, I should have mentioned that yes, the xServe will be sharing the storage out via 2 bonded Gb ethernet ports.

We don’t really care how it is connected…iscsi, FC, mini-SAS, or whatever. Just has to be at least as fast as the current system.

I think I am not going to go the Drobo route. It just hasn’t been fast enough in our tests. But I am really interested in the SAS approach. Is there a turn key solution? I have never used nor researched the SAS solution, but that sounds like it would work.

[Stephen Davies]

Craig,

There are many options that you can consider to replace the Xserve RAID. The “easiest” thing to do would be to get another FC RAID array which would simply sit in place of the Xserve RAID. Most newer designs feature 4Gb FC connections and support SATA and/or SAS drives so you would expect to get much better performance (assuming that the FC HBA in your Xserve is capable of 4G wire speeds. If not you could still operate at the existing 2G speed and have extra “umph” if you want to upgrade the HBA later on.

You could also go with an iSCSI RAID array (you should look at one that supports “bonding” of multiple ports) or even SAS RAID units. Either of these would vastly increase the performance of your existing set up but they would require that you also add an appropriate HBA to your server.

Why don’t you check out our web site (https://www.proavio.com) as we have a lot of products that could be very useful in just this kind of environment. Our RS series, in particular, is available in either 8 or 16 drive configuration (up to 24TB for 8 drive or 48TB for 16 drive) are are available with either FC, iSCSI or SAS interfaces.

Stephen Davies
Technical Sales Representative
PROAVIO USA

[Craig Wolf]

Stephen.

Yes, exactly our thoughts. Initially we were going to replace the xServe RAID with a promise vtrak, buy a 4Gbs HBA, and keep the xServe RAID installed on the 2Gbs card for backup.

I will visit your site now. The 8 drive array might be what we are looking for. If just based on hooking up to one server, what would be your recommendation (knowing either way we’ll need a card to hook up to it with) … iSCSI, FC, or SAS?

Thanks again.

[Craig Wolf]

Stephen.

I don’t see the RS series in here.

https://www.proavio.com/products.html

Ultrastor, IS316JS, or Studiorack? Also, while not required, we would prefer rack mounted options. Thanks again.

And I appreciate the responses from everyone even though this isn’t creative/video focused. Much appreciated.

[Alex Gerulaitis]

[Craig Wolf] “Ultrastor, IS316JS, or Studiorack? Also, while not required, we would prefer rack mounted options. Thanks again. “

An S8MS StudioRack would work (with a MiniSAS RAID controller) although I’d recommend an expandable solution, and I think Fibre-Channel would work the best given the existing hardware: ES16FS. I’ll check on pricing if you’d like me to.

Alex Gerulaitis
Systems Integrator
DV411 – Los Angeles, CA

[Alex Gerulaitis]

[Craig Wolf] “We don’t really care how it is connected…iscsi, FC, mini-SAS, or whatever. Just has to be at least as fast as the current system. “

Mini-SAS is generally the fastest and the least expensive way to attach storage:

– 24Gbs aggregate line speed via a single MiniSAS 6Gbs port
– inexpensive cabling (up to 10m)
– costs approx $2K less than a Fibre-Channel solution (from ground zero)
– Direct-Attach (DAS) only

Fibre-Channel:
– 16Gbs aggregate line speed via dual 8Gbs ports
– negligibly more expensive cabling given total costs, much longer cable runs – 100s of meters
– DAS or SAN (SAN with a switch and management software)

Alex Gerulaitis
Systems Integrator
DV411 – Los Angeles, CA

[Rainer Wirth]

I’ve replaced two Xserves two years ago.
I’ve a sonnet R800 (8 drives) with SAS (very fast and reliable) and a 4x8gb FC Axus Yotta raid 24bay. I still use one of the Xserve raids for the render files. All raids have 3TB Hitachi HUA hard discs. To me the best you can get. No problems until now. If you need more than one Workstation (Server) you have to use Fibrechannel raids. Sonnet, active storage, small tree, Axus, dulce. I wouldn’t go for Promise (tech specs). But this is just personal choice.
The drives you use in the raid configuration are important. Get the best drives you can buy. A raid is there to work and forget about it.

Rainer

I still think that the Xserve Raids are a very good piece of hardware – working working working

[Stephen Davies]

Craig,

There are a number of factors that need to be considered when when selecting the appropriate type of storage and/or storage data interface. Obviously, price is going to play a big part in it but performance, ease of integration/management and potential for future expansion are also going to have an important place in the final decision process. Ultimately, you will need to find a “comfortable” balance between these for your particular environment.

Deciding between an “internal” RAID (external JBOD storage array with an plug-in RAID controller in your server) and a purely external solution (RAID controller built-in to the storage array) is a little subjective. A JBOD array is definitely cheaper than an external RAID system; however, you will also need to factor in the cost of the internal RAID controller to get a true comparison. However, a JBOD solution is completely dependent on the workstation/server so a failure there could be disastrous for your stored data. An external RAID is completely independent and “agnostic” of the host computer so data is a little more secure and you could even swap out the entire host system without affecting the storage. Expansion is also typically more common with external RAID systems. Finally, integration is definitely easier with an external RAID system; JBOD systems require the integration of internal hardware, loading and configuration of appropriate drivers, etc.

The type of data interface will largely be driven by your performance requirements, although ease and convenience of integration will also play a part. For the most part, there are 3 predominant interface types that you can choose from; Fiber-Channel, iSCSI or SAS (for internal systems SAS is really your only option). iSCSI is, without doubt, the easiest to integrate as it simply plugs into one or more of the existing LAN ports on your computer. However, most iSCSI RAID systems are limited to GbE so performance will only be about 70MB/s. You can increase this by “bonding” multiple ports (link aggregation) but this would require a storage system that supports multiple data ports (such as our RS series) and may require the addition of a multi-port NIC to your server.

At the other end of the spectrum is the SAS interface. By far, SAS will give your the best data throughput potential of all of the available interfaces. However, you will need to add a SAS interface to your workstation/server so you’ll have to add that cost to the overall price of the solution. Maximum cable lengths for SAS are also a lot shorter than either GbE or FC, so that may be a factor.

Finally, Fibre-Channel (FC) stands somewhere between the other two interfaces. FC is definitely faster than GbE but is nowhere near as fast as SAS. FC also shares the extreme cable length capabilities of GbE but does require fairly expensive interface hardware to be added to you computer. In your case, however, you already have an FC controller in your server so that could make a fibre-channel solution a viable alternative for you.

If you need to get more information on any of the ProAVIO products, you can find full information on the Enhance Technology (https://www.enhance-tech.com) web site (Enhance is our parent company).

Thanks.

Stephen Davies
Technical Sales Representative
PROAVIO USA