Monday, June 16, 2008

Closet WO Developer

One of many hats I wear is that of a erstwhile java developer. Our internal apps have been heavily reliant on object relational mappers. I've dabbled into RoR, and even helped get a TurboGears project off the ground here that was fully open source. However, the primary solution we've used in production since 2002 has been the grand daddy of ORM solutions: WebObjects.

This past week at Apple's WWDC was a great one for WebObjects. The usual NDA applies. However, prior to that the WebObjects community had their own two day in-depth conference in San Francisco. No NDA for that, and I can report that WO development is alive, well, and dare I say thriving? The news about SproutCore has a second story, in that the backend of choice may be RoR, but the #1 apps will likely also be WO-based. Got an iPhone? Learn WO. As we opensource some of our projects here, I'll write a few more posts and speak on some more points, but with the latest release of WebObjects (5.4.x) the final deployment restrictions on the free WO frameworks were lifted. I expect some level of renewed interest.

To find out more, check in with the WOCommunity.

Wednesday, June 04, 2008

Recommended Disk Controllers for ZFS

Since I've been using OpenSolaris and ZFS (via NexentaStor, plug plug) extensively, I get a lot of emails asking about what hardware works best. There have been various postings on the opensolaris and zfs lists to the same effect. A lot of people reference the OpenSolaris HCL lists which leave the average user scratching their head with more questions than answers. More to the point, the HCL doesn't tend to answer the more direct question of what hardware should I get to build a ZFS box, NAS, etc. Its important to note that in the case of ZFS, all that extra checksum, fault management, and performance goodness can be negated by selecting a "supported" hardware RAID card. Worse yet, many RAID cards are not fully interchangeable on the spot. What do you want for ZFS?

First, pick any 64-bit dual core or better motherboard or processor. If you can get ICH6+, nvidia, or Si3124-based on board SATA, then you are in good shape for your basic ZFS box with on-board SATA for your system disks alone. System disk can tend to be low 5400RPM 2.5 inch SATA-I drives. Many people then desire some large memory, battery-backed RAID card, and my tests with the high end LSI SAS cards show that memory on the RAID card doesn't do you as much good as having a recipe of lots of system RAM, a sufficient number of cores, many disk drives for the spindles, and sufficient use of the PCIX/PCIe bus using JBOD only disk controllers. I'll cover the controllers next, but I'd recommend at this point 4GB of RAM minimum, dual core at greater than 2ghz, and for any good load, at least two PCI-X or multi-lane PCIe card.

Disk controllers are where the real questions are asked. Over multiples iterations, heavy use, and some anecdotal evidence, we are down to some sweet spots. For PCI-X, there is one game in town, the Marvell-based AOC-SATA2-MV8, used in the X4500. At $100 for 8 JBOD SATA-II ports, it just works and is fault managed. Stick just SATA-II disks on these, and keep any SATA-I disks on the motherboard SATA ports for system disks. I'll add that various Si3124 based cards exist here, but not for sufficient port density.

SuperMicro AOC-SATA2-MV8 link

When it comes to PCIe, there isn't any good high port count options for SATA. If you need just 2 ports, or eSATA, there are various solutions based on the Si3124 chipset, and SIIG makes many of them for $50 each. However, in the PCIe world, the real answer is SAS HBAs that connect to internal or external mixed SAS/SATA disk chassis. Again, most SAS HBAs are either full fledged RAID without JBOD support, or simply don't work in the OpenSolaris ecosystem. 3ware is a lot cause here. The true winner for both cost and performance, while providing the JBOD you want, is the LSI SAS3442E-R.

CDW catalog link for LSI 3442ER
LSI 3442ER product page

Its $250, but I've seen it as low as $130. 8 channels, with both 2 internal ports (generally 8 drives are connected to a single SAS port) as well as the external port. You can use this with an external SAS-backed array of SATA drives from Promise, for instance, to easily populate 16 or 32 drives internally, with an additional 48 drives externally, just from the one card. Would I suggest that many on that single card? No, but you can. Loading up your system with 2 or 4 of these cards, which are based on the LSI 1068 chipset that is well supported by Sun is the best way forward for scale out performance. I was given some numbers of 200MB/sec writes and 400MB/sec reads on an example 12-drive system using RAIDZ. Good numbers, as I got 600MB/sec reads on a 48-drive X4500 thumper.

If you have PCI-X, go Marvell. PCIe? Go LSI, but stick to the JBOD-capable not-so-RAID HBAs. Don't just trust me, throw a $100 or two at these and try it yourself. You'll see a better investment than $800 at the larger RAID cards. I went the latter route and have paid dearly (Adaptec, LSI, you name it). What worked from the beginning and is working today are the Marvell cards here, and I've been playing with new systems that use the LSI 3442ER.