Sunday, December 12, 2010

Windows Backup Error 0x81000019

Recently, I've been getting an error from Windows Backup:

Error Code: 0x81000019

Event Viewer lists the following additional information:
Shadow copy creation failed because of error reported by ASR Writer. More info: The requested system device cannot be found. (0x80073BC3).

Volume Shadow Copy Service warning: ASR writer Error 0x80073bc3. hr = 0x00000000, The operation completed successfully.

PrepareForBackup event

Execution Context: ASR Writer
Execution Context: Writer
Writer Class Id: {be000cbe-11fe-4426-9c58-531aa6355fc4}
Writer Name: ASR Writer
Writer Instance ID: {5c8b67a8-a665-45e5-9f5c-45382f136693}

Error-specific details:
ASR Writer: The requested system device cannot be found. (0x80073BC3)

Volume Shadow Copy Service error: Unexpected error calling routine Check OnIdentifyError. hr = 0x80073bc3, The requested system device cannot be found.

PrepareForBackup event

Execution Context: ASR Writer
Execution Context: Writer
Writer Class Id: {be000cbe-11fe-4426-9c58-531aa6355fc4}
Writer Name: ASR Writer
Writer Instance ID: {5c8b67a8-a665-45e5-9f5c-45382f136693}

Error-specific details:
ASR Writer: The requested system device cannot be found. (0x80073BC3)

Fault bucket 668258104, type 5
Event Name: WindowsBackupFailure
Response: Not available
Cab Id: 0

Problem signature:
P1: Backup
P2: 6.1.7600
P3: 0x81000019
P4: 7

Attached files:

These files may be available here:

Analysis symbol:
Rechecking for solution: 0
Report Id: 8b57e781-0633-11e0-a042-90e6ba2d22c8
Report Status: 0

Backup did not complete successfully because a shadow copy could not be created. Free up disk space on the drive that you are backing up by deleting unnecessary files and then try again.

And what does it all mean? Well, I just recently installed a new hard disk and installed an alternative OS onto it. This new hard disk is appearing as "Disk 0" in Disk Management and it *is* the boot device. When I boot off it and then select my Windows partition I get these error messages. It appears VSS attempts to access/lock the drive that booted the OS and it fails. If I attempt to take "Disk 0" offline, I get the following error message:
Virtual Disk Manager
Disk attributes may not be changed on the current system disk or BIOS disk 0.

Using Procmon I can see that VSSVC.exe attempts to access a filesystem that it cannot... Well, the only disk that it can't access is the lone "Alternative OS" disk. I suspect removing that disk or forcing my BIOS to boot directly to the Windows partition will resolve my issues. If you're in a similar situation as me, I would suggest checking your boot order, removing any extraneous disks or ensuring your boot drive is appearing as "Disk 0" in disk management.

I've just tested and confirmed that forcing my BIOS to boot directly to my OS drive without going through an alternative drive has enabled the backup program to operate without any errors.

This blogpost is for anyone else that my experience a similar issue.

Thursday, December 02, 2010

DataRAM RAM Disk Review (part 2)

I've purchased some RAM to replace my 1GB sticks. This new RAM allows my system to operate at 1333MHz DRAM speed without issues. So, I've set my RAM to this new bandwidth speed and my memory went to:

14099MB/s Read, 12034MB/s Write, 16901MB/s Copy.

This represents an improvement of:

23% Read, 0% Write, 10% Copy.

With a 23% Read performance improvement will DataRAM's RAMDrive solution improve?

It does not.

It appears something else is holding the performance of the RAMDrive software down. IOMeter *did* see some improvement (from 5000Mb/s to 5094MB/s... a 1.9% improvement) but pretty insignificant from what it *should* be, if it was hardware being the hold up.

The "bandwidth" of the RAMDrive is 40Gbps, a pretty large leap from the maximum you could get from SATA at it's best (6Gbps), but I hope DataRAM investigates what the performance ceiling is of their software and can explain or correct what's causing it.

Overall though, I'm still happy with the software and for a free 4GB RAM disk or $10 for a maximum of ~64GB, I think it's a great value. I have 18GB of RAM in my system and utilize this software for programs like StarCraft or VMWare machines and the loading speeds are great.

Wednesday, December 01, 2010

Dataram RAMDisk Review

I've purchased a product called Dataram RAMDISK and am going to do a quick review on it. It's free for RAM Disk's up to 4GB in size. Beyond that size and you need to pay $9.99 for a license file that allows you to increase it to whatever amount of free RAM you have in your system up to a maximum of 64GB. My system is a P6T SE with 6 RAM slots, 3x2GB RAM and 3x1GB RAM sticks are installed, giving me 9GB in total. This configuration activates triple-channel mode, so I'm getting the full 192bit of available bandwidth from my memory.

All of my RAM is DDR3 @ 1333MHz (PC3-10600), but Everest is reporting a speed of 800MHz. My theoretical MB/s speed should max out at 32000MB/s, but if Everest is only operating at 800MHz that means my theoretical maximum speed is 19200MB/s. I think the reason I did this is because my triple channel puked at the unmatched channels causing BSOD's and non-boots, but I'll investigate later as it's a huge performance penalty. Everest confirms this is the measured speed I'm running at 19200MB/s

(Everest measures 19198MB/s)

(My unmatched odd sets of RAM pairs. Note, 1333MHz is the lowest my RAM goes, to 1800MHz for the fastest).

With that said, my current theoretical maximum speed my RAM should be able to operate at is 19200MB/s. I'm going to test my RAM first to gauge it's maximum speed, then test the RAM Disk to see if it matches up.

Everest reports that my actual performance is 11446MB/s Read, 11978MB/s Write and 15376MB/s Copy. The Memory Read benchmark reads a 16 MB sized, 1 MB aligned data buffer from system memory into the CPU. Memory is read in forward direction, continuously without breaks. The Memory Write benchmark writes a 16 MB sized, 1 MB aligned data buffer from the CPU into the system memory.

I will attempt to duplicate these with IO Meter to see how close the RAMDisk can get to the theoretical benchmark.

Before that, he's Everest Disk Benchmark result (everything is automatic - Linear Read):

With IOMeter I have the following configuration:
Size 1MB
Access 100%
Read 100%
Burst 1
Alignment 1MB
100% Sequential
Align I/O's 1MB

The results I get are:
5000 I/O per second
5000 MB/s

Swapping Read 100% to 0% (making it 100% Write) I get:
4930 I/O and MB/s

So writes are more intensive then reads, as they usually are, but I cannot get anywhere close to the speed of reading a 16MB sized file in 1MB chunks to the maximum theoretical speed of the RAM. I'm unsure as to why that may be, but I suspect it's the path the file takes from the RAMDisk -> Driver -> Bus -> CPU...?

To try and maximize the speed of the drive and match up to Everest Linear read to gauge the maximum speed of the disk, I'll setup IO Meter to match Everest's description of the Linear Read test:
This test is designed to measure the sustained linear (sequential) reading performance of the storage device by reading all data from the surface of the device.

IOMeter does this easily enough.

Using Procmon, I was able to verify that Linear Read uses a 64KB block size and reads the entire disk. Doing this with IO Meter I achieved the same results as above in the MB/s, but much higher IO/s. I'm unsure why IOMeter is unable to match Everest's results.

HD Tach was not useful as it would operate at 3000MB/s for various lengths of time each time I reran the test. Sometimes it would operate at 3000MB/s up to 0.5GB then 700MB/s for the rest of the drive, or 3000MB/s up to 2.4GB.

Too inconsistent to make an observation.

To compare this RAMDisk to other HDD's I turned to Anandtech and used his settings to compare some SSD drives. His results are here.

The results I achieved are:
133362 IOs per second
522 MB/s
Average Write Latency 0.0073
Max Write Latency 0.5526

Compared to the first gen Intel SSD's the RAM Disk is:
12x faster in IOs per second
12x faster in MB/s
12x faster in Average Write Latency 0.0073
170x faster in Max Write Latency 0.5526

Pretty much an order of magnitude faster as should be expected for a RAM Disk vs. a top of the line SSD.

In the end, I'm unsure if I've hit a wall with my numbers, but it feels artificial. Everest does come within 70% of the numbers it achieved in a pure memory test, but even the Everest test tops out at exactly 8192MB/s.

I'll try changing my memory speeds to something faster and see if this limit is artificial or a limit of my system.