iSCSI - The right way to go?

[hambo12]

I have a new backup server attached to a Tape autoloader.

I want to setup D2D2T to stage backups to our new SAN, then to Tape.

However, I cant seem to find a speedy way to get to the SAN from the bakcup server. My boss suggested iSCSI.

I have zero experience with iSCSI, so I guess im asking, is this the best solution for connecting to the SAN??

 

[LeeMason]

What sort of SAN do you have. Do you need to backup via each host or can you access the SAN disks directly via fibre channel connection?


Lee Mason
Optimal Projects Ltd

http://www.opl.co.uk

http://www.backupsanywhere.com

 

[robbym627]

We use iSCSI for our SANs and I find it to be a good solution. Best way to set it up though is to use jumbo frames point to point for the best results.

 

[RMGBELGIUM]

Iscsi is ideal for a cheap and rather performant production SAN. But when you are talking backup, the BU windows are getting smaller and smaller, and data keeps on growing.The goal is to move as much data as fast as possible to the BU device, so now we're talking Fiberchannel 4Gbit.with iscsi you are never going to get speeds up to 600 or 800 MB /sec as is often needed when having to dump terabytes of data in a small interval.

rgds,

R.

 

[xmsre]

With jumbo frames, the payload can be up to 9000 bytes. iSCSI is great for applications that have a small IO size. Exchange and SQL are examples. With a small IO size of 4K or 8K, you're never going to saturate the media. As the IO size increases, FCP begins to show the advantages of a faster media. At a 64K IO size, 2G FCP is going to have much higher throughput than 1Ge ISCSI. Most backup applications read in 64K chunks. FCP will be faster.

Of course the media isn't the only potential bottleneck. You have to consider how fast is the target disk? How fast can you pull data off your application server without impacting the application? It's really a matter of how many spindles you have and the the RAID configuration (calculate the write penalties when you stage the data to SAN) Once you have the data on disk, how fast can you read it from disk and write it to tape?

 

[NickFerrar]

As you already have a server-attached tape drive then yeah iSCSI connecting the server to the SAN seems the obvious choice. We use a FC tape library directly attached to the SAN and then multiple servers can backup directly to it which is a lot quicker but also a lot more expensive to set up. For a client we're doing the server attached tape library + iSCSI thing and it seems to work fine (it only needs to backup around 600GB though so it's not really being stressed).
I'm hoping Dell come out with an iSCSI version of the ML6000 tape library soon to...