Monday, April 1, 2013


> Realm shutdown

Click on the picture for high resolution. Today we decommissioned the only 10gbit Intransa iSCSI storage realm in existence. There were only two ever built, and only one was ever sold. This one was built by Douglas Fong for use by Intransa IT and has 24 4-disk IP-connected disk shelves in six cabinets, for a total of 96 250gb IDE hard drives talking to two SMC/Dell switches via 48 1gbit connections. The SMC/Dell switches are then connected to the two clustered controller units via 10Gbit Ethernet, which then exports iSCSI to the two SMC/Dell switches above it via 10Gbit Ethernet. This whole concept was designed for scale-out storage, when you needed more storage you just added more of the blue boxes (or, later, the grey boxes to the left) and incidentally this also made the result faster.

Two things became clear as I was prepping the changeover from this 2/3rds rack of equipment to 4u worth of generic Linux storage. The first was that the Intransa box was infinitely easier to manage than my 24 disks worth of Linux-based storage, despite having four times as many spindles. This is because the Intransa software did policy-based storage allocation. You told it you wanted a new volume with 5-disk RAID5 or 4-disk RAID10 or whatever, and it went out and either found existing RAID groups and put your new volume there, or found enough disks to create a new RAID group and put your volume there. You didn't have to worry about how to lay out RAID groups or volumes on top of RAID groups and exporting to iSCSI, it all Just Happened.

The second thing that became apparent was that this beast was fast -- seriously fast. The orange cable at the top right is the 10Gbit Ethernet cable going to my new infrastructure that I used to migrate the volumes off of this pile of blue boxes. Surprisingly, the limit was my new Linux storage boxes, not the Intransa storage -- I was pulling data off at 200 megabytes/second, the max I could pull in via my two 1Gbit Ethernet connectors. It seems that if you have enough spindles, even 250gb IDE drives can generate a significant number of iops. It would have been interesting to see exactly how fast it was, but unfortunately I'm still working on getting the Intel 10Gbit cards working in the Linux storage servers (I am now going to use copper SFP+ cables, since it is clear that the Intel cards aren't going to work with the optical SFP+ modules that I have), so was restricted to two 1Gbit connections.

Sadly, the pile of dead drives on top of the pile of blue cabinets are one indication of why it's being retired. The 250Gb Maxtor drives in this thing were manufactured in 2004 and were starting to fail. My supply of spare parts was limited. In addition, this beast is horrifically complex -- even the person who built it had trouble getting it up and running the last time it was moved, and our new little startup certainly wouldn't be able to get it up and going by ourselves, so we settled for getting the intellectual property off of it onto our own generic Linux server equipment. Finally, it and the backup replica realm beside it took up a huge amount of space and power, the two Linux servers do in 8U what required an entire rack full of equipment to do with this seven-to-nine-year-old Intransa equipment. So it was time, albeit with a bit of sadness too. Intransa had some great ideas and solid gear. They could not, alas, make money with it.

I played taps on my Irish whistle as the realm shut down.

-- ELG

No comments:

Post a Comment