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// Tales from software development

Archive for May 2008

Adaptec RAID 1220SA card

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If the price of an Adaptec RAID 1220SA card seems suspiciously low, you might be right to be wary.

I’m in the process of configuring a server that will be used as a VM host. I thought it’d be a good idea to have a lot of disk to store the Virtual Hard Disk (VHD) files and had chosen a 1Tb Samsung Spinpoint as the second disk. Securing a 1Tb disk might be difficult so I decided that a second 1TB disk and a RAID controller to mirror the disks would be the answer.

I checked a couple of online retailers and bought the Adaptec RAID controller that seemed to be the best fit for my needs. The Adaptec RAID 1220SA is a 2-port SATA PCI-Express adapter. It’s quite cheap at around £40 ($79) but it’s been a long time since I bought an entry level RAID adapter and I assumed that this was the going rate.

I installed the card and setup the two drives in a RAID 1 configuration using the card’s BIOS utilities. The build of the array took 40 hours which was a pain but worse was to come. The array seemed quite fragile and the card reported that the array was in SUBOPTIMAL state several times for no obvious reason. Each time I tried to correct this something else happened that sapped my confidence in the card.

At this point I should mention that I am running Windows Server 2008 on this server and that Adaptec don’t yet have a driver for the 1220SA on this OS. Windows had identfied the card as new hardware and selected and installed the Windows Server 2003 driver on the installation CD.

The first attempt to rebuild the array (another 40 hours) appeared to be successsful but very soon afterwards the card reported the array status as VERIFY. I attempted to Verify the array using the card’s BIOS utilities but this hung after a few hours. I deleted the array and recreated it and this time used the QUICK-INIT option. This creates the array immediately but requires that a Verify operation is then run. I booted into the OS and started Adaptec’s Storage Manager software. I selected the Verify operation against the array and resigned myself to waiting another 40 hours for this to complete. However, when I checked on the status of the Verify 10 minutes later, there was no sign of the array in Storage Manager. The array had just disappeared! Checking back through the application’s event log, there were messages indicating that the two disks had been removed from the system (they hadn’t) and that the array had been deleted. The event log then showed disk defects being discovered and repaired every second or so but the bad block address was always the same. I restarted the machine and started the BIOS utilities again. This time I selected the Disk Verify option and both disks verified successfully (8 hours for each) indicating that there were no disk errors. Things never really got much better than this. The few times the OS started up with the array intact, the disk was often flagged as READ-ONLY by the OS and needed convincing using DISKPART that it was actually writable.

After a week of of these problems I was ready to ditch the card and give up on the RAID idea all together. If an Adaptec card was giving me this much trouble then I didn’t even want to think about what a no-name brand card would be like.

Before I gave up completely I browsed Adaptec’s web site to see what the alternatives were and slowly the truth dawned on me. The 1220SA is not a RAID Controller at all. It’s a RAID Host Adapter. This Adaptec terminology indicates that the 1220SA is little more than a storage controller that ships with an OS driver that implements RAID. In otherwords, this is software RAID not hardware RAID. Adaptec calls this technology HostRAID™.

This terminology is demonstrated clearly if you select the Products drop down menu on the main page of Adaptec’s web site at http://www.adaptec.com. Two thirds of the way down the list, just after Snap Servers, you’ll see RAID Controllers followed by Host Adapters. The RAID 1220SA card is listed under Host Adapters not RAID Controllers.

Now I can see that the lack of a driver for Windows Server 2008 might be a bigger issue than I had previously thought it was. I had assumed that the 1220SA was a hardware RAID card and that the driver was simply to access it as a storage controller. In fact, the driver is actually responsible for the RAID processing. Quite apart from the fact that software RAID is generally slower and places an additional load on the CPU compared to hardware RAID, I’m also concerned that an OS crash with the 1220SA is going to compromise the integrity of the RAID array.

The cheapest RAID Controller option for me, as I need a PCI Express card with at least two SATA ports, is the new Adaptec RAID 2405 Controller. This offers 4 SATA ports on an x8 PCI Express card. The card has only just been announced and the expected UK price is £116 ($230), or nearly three times the cost of the RAID 1220SA. After my experiences with the RAID 1220SA, the RAID 2405 is reassuringly expensive and I’ll be buying one as soon as I can find one.

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Written by Sea Monkey

May 28, 2008 at 8:00 pm

Posted in Hardware

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Would you butter your toast with a scalpel ?

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Steve, Dav, and I were having our usual daily car discussion. Dav’s seemingly endless search is for a used car that has the performance of a Ferrari, sounds like a Ferrari, and is comfortable and practical – on a budget of less than 30K. Arguably, his current car, a Golf R32, is a good compromise. Steve’s 911 C2 would seem to be another good choice but Dav doesn’t like the exhaust note, the fact that the engine is over the back axle, and the seats give him back ache.

I’ve always favoured much more focused cars like the Caterham 7 and the Elise and modern mainstream sportscars like the S2000. My preference is for a stripped out, lightweight, car and I’m prepared to compromise on comfort and practicality. I’ve never understood why people find it so hard to lose their creature comforts such as leather seats and air-conditioning.

But Dav came up with a simple and effective analogy that illustrated the problem: “Would you butter your toast with a scalpel ?”

Written by Sea Monkey

May 21, 2008 at 7:30 pm

Posted in Comment, General

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Can't RDP to a VM ? Is Port 137 blocked ?

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Port 137

I’d just created a virtual machine and installed Windows 2003 server but when I tried connecting to the VM using Microsoft’s remote desktop client but it failed. On the VM, Windows Firewall was turned on but the ‘Remote Desktop’ exception was enabled, so why was the connection failing ?

I tried turning off Windows Firewall to see if it made a difference. It did – the RDP client connected immediately. If I turned Windows Firewall back on, any subsequent attempts to connect to the VM also succeeded. This suggested some sort of name or address discovery issue.

As I had already enabled logging in Windows Firewall I checked the log and found that it dropped several incoming requests on Port 137:

|date       time              src          dst           src dst size
|                             ip           ip            prt prt size
|2008-05-03 15:10:19 DROP UDP 192.168.0.12 192.168.0.255 137 137 78 - - - - - - - RECEIVE
|2008-05-03 15:10:20 DROP UDP 192.168.0.12 192.168.0.255 137 137 78 - - - - - - - RECEIVE
|2008-05-03 15:10:21 DROP UDP 192.168.0.12 192.168.0.255 137 137 78 - - - - - - - RECEIVE

The log shows that the computer with IP address 192.168.0.12, which is the machine that I was running the RDP Client on, sent three  broadcast requests on the local subnet (192.168.0.255) to port 137.

Running ‘netstat -a -n -o’ at a command prompt on the target computer shows:

Active Connections
Proto  Local Address          Foreign Address        State           PID
...
UDP    192.168.0.15:137       *:*                                    4
...

So, the process with ID 4 is listening on port 137. We can find out which process this is by running the the ‘tasklist’ command at a command prompt:

Image Name                     PID Session Name        Session#    Mem Usage
========================= ======== ================ =========== ============
System Idle Process              0 RDP-Tcp#1                  0         16 K
System                           4 RDP-Tcp#1                  0        212 K
...

So, the process with ID 4 is actually the system process. It’s likely that port 137 is being used for a normal system function that Windows Firewall is blocking.

A quick search on the internet indicated that this port and protocol is used by NETBIOS. Now it makes sense – because I’m not using a domain, when I tried to connect to the target computer by name, Windows broadcast a request for the computer with that name to identify itself.

My initial thought was that I should define a new exception for port 137 but then I realised that because this is a common network protocol, there was almost certainly an exception already defined. I just needed to find out what it was and enable it.

Among the other exceptions available in Windows Firewall but not currently enabled was ‘File and Printer Sharing’. Selecting this exception and clicking the Edit button displays the ports and protocols associated with this exception and one of them is UDP on port 137. Enabling this exception resolved the problem.

Still can’t connect ?

Some of the more common issues that can cause a failure to connect to a VM, or any machine for that matter…

Remote Desktop is not enabled

The most obvious cause but worth checking. The ‘Enable Remote Desktop on this computer’ option should be enabled on the Remote tab of the System Control Panel applet.

Port 3389 is blocked

RDP uses TCP on port 3389 on the server machine. If you’re using Windows Firewall this is opened by enabling the Remote Desktop exception shown on the Exceptions tab of the Windows Firewall Control Panel applet.

VM has dropped off the domain

If you use VMs in a domain and you have connectivity issues then it’s worth checking that the VM hasn’t dropped off the domain.

This can be a surprisingly subtle problem as the VM doesn’t make it obvious that it is no longer on the domain. The problem usually manifests itself as no connectivity – you cannot connect using RDP or even file shares. The server machine will still respond to pings but that’s all.

If you logon to the server using the Virtual Server VMRC, or the hardware console if this isn’t a VM, and display the users in the Administrators group you’ll see a load of SIDs instead of whatever domain users you’ve added to the local administrators group.

You’ll need to re-add the machine to the domain as described in What credentials should you use when joining a domain ?

Written by Sea Monkey

May 10, 2008 at 1:23 pm

Posted in Environments

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Where are we now, or, what can you get for £99 ?

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Last week I bought a new Dell SC440 PowerEdge server that was on special offer at £99. This is for a complete ‘box’ (with processor, memory, disk, etc.) but without the keyboard, mouse, and monitor.

It seemed almost too good to be true so when it arrived this week I was pleased to find that there was no catch and it really was a great deal. It got me thinking about how cheap computers have become in the past few years…

The first computer I owned was a second hand Sinclair ZX Spectrum. It was 1983 and the price of a new 16K model had just dropped from £125 to £99 but I bought an early 16K model with the 32K RAM extension for £80 from a work colleague.

So, in 1983, £99 bought you a new home computer with:

Zilog Z80 3.5Mhz 8 bit processor
16Kb of memory
Video adapter (RF output to television) with a resolution of 256 x 192 pixels and 4 bit colour depth (16 colours).

There was no non-volatile storage media but you could hook up a cassette recorder to load and save programs.

So, 25 years on from the Spectrum, was does £99 buy these days ?

Intel Dual Core 1.8Ghz processor 32 bit processor (with 64 bit extensions)
512Mb RAM
160Gb SATA disk
DVD-ROM drive
Integral video card giving up to 1920 x 1200 resolution at 32 bit colour depth

It’s diffcult to assess the relative power of the processors but in terms of raw speed, the Dell is running over 500 times faster than the Spectrum and has over 16,000 times as much memory. If that doesn’t sound impressive enough, consider that the difference in processor speeds means that the Dell is running 52,000 per cent faster than the Spectrum.

The hard disk and DVD-ROM drive are devices that I could only dream about in the days of the spectrum. Actually, I did eventually buy a hard disk for the spectrum. I forget the details but it was more expensive than the Spectrum itself and had a capacity of just a few megabytes.

With the effect of inflation over the past 25 years, £99 today is not worth what it was in 1983. Using the Retail Price Index as a guide to inflation, a rough calculation indicates that the equivalent value today of £99 in 1983 is £250. So, my new Dell is not only a lot faster and more capable but is actually only 40% of the cost of the Spectrum, or the equivalent of £39.60 in 1983 pounds.

Incredible… 

Written by Sea Monkey

May 3, 2008 at 7:45 am

Posted in Comment, Hardware

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