RAM Disk Puts New Spin On the SSD 305
theraindog writes "Although the solid-state storage market is currently dominated by flash-based devices, you can also build an SSD out of standard system memory modules. Hardware-based RAM disks tend to be prohibitively expensive, but ACard has built an affordable one that supports up to 64GB of standard DDR2 memory and features dual Serial ATA ports to improve performance with RAID configurations. And it's driver-free and OS-independent, too. The Tech Report's in-depth review of the ANS-9010 RAM disk pits it against the fastest SSDs around and nicely illustrates the drive's staggering performance potential with multitasking and multi-user loads. However, it also highlights the device's shortcomings, including the fact that SSDs are more practical for most applications."
In summary (Score:5, Informative)
Skimming the article, I'd summarize as follows:
Real world performance not radically better than fast traditional HDs or SSD solutions, and you can't power off your PC for the night. (Unless you backup to flash every night.)
I'd say this is a niche product, but could be a very good one for a chosen few applications.
Not that impressive (Score:2, Informative)
Re:ahh 1993 was a good year (Score:3, Informative)
These days you can just use iSCSI to any free Unix-like and export a memory-backed virtual disk. It's also a nice way to use one machine's memory as swapspace for another, and with a fast network link it's like having more RAM in the client machine.
Re:Being more practical is a bad thing??? (Score:1, Informative)
Since when is being "...more practical for most application..." considered a shortcoming?
I think the artical meant the FlashDrive bases SSDs, not the memory bases SSDs. Why the artical uses the term SSD, which points to both types of disks I do not know.
Re:No ECC... (Score:2, Informative)
Actually, this box supports it's own ECC function. If you use ECC RAM, the ECC function is just like a normal ECC function. However, if you don't want to spend extravagant prices for ECC RAM, the box will create it's own ECC function. This function does use 1/9th the total RAM, but it is ECC, and it works. I own 3 of these boxes right now. They are fast as heck. I haven't played with SSD much(my first SSD drive arrives in the mail today), but I was able to perform tasks at performances that were beyond comprehension. From the time I double clicked the executable to the computer completely rebooted after the install was less than 2 minutes. Currently, Windows XP with all the standard software installed is less than 30 seconds.
Re:Great for swap and /tmp (Score:4, Informative)
My apologies - forgot I wasn't supposed to RTFA.
Re:Great for swap and /tmp (Score:5, Informative)
If you compare this thing to just putting the RAM in your PC there are NO upsides.
Ok...
1. Find me a motherboard that has 8 RAM slots that doesn't require expensive ECC and/or Registered memory
2. Find me a computer that can boot from it's own RAM drive.
3. Find me a computer that can use a RAM drive that can be persistent through reboots without having to save the contents to something else.
I have several of these, and I run a power cord that is normally used for one of those SATA/IDE to USB kits in the back of my computer to power my box.
You don't think about all of the uses that this thing offers.
failure mode (Score:3, Informative)
How does this thing handle getting the power cord yanked in the middle of a large write operation?
Son of iRAM (Score:5, Informative)
A few of the things it improved on the old iRAM.
*DDR2 supported ram, with 6-8 slots, taking up to 4G sticks.
*A fair sized battery.
*A CF backup slot.
*RAID friendly, multiple SATA ports on 8 slot model.
*Uses 5.25" bay rather than PCI slot.
*ECC
First off, no special device driver was needed - the drive was OS agnostic. Every mainboard and controller card I used saw it the device like any other SATA hard drive you might plug in.
The RAM slots take bog standard DDR2 RAM. The documenation mentions speeds of 400/533/667/800 are all supported. Benchmarks with 533 and 800 grade RAM produced identical benchmarks, so faster RAM does not appear to have any impact. I also mixed and matched faster and slower DDR2 modules without issue.
Just like most mainboards, the RAM needed to be installed in pairs if over one stick was used.
Unbuffered ECC or non-ECC modules are both supported. Registered RAM was not. I tried to pull eight 4GB sticks from one of my Sun boxes to give the 'full montey' test. No joy. Had to stick with the far cheaper RAM.
There was an interesting option for these who wanted to have ECC but used 'regular' non-ECC RAM. Eleven percent of the memory could be reserved for error correction. Again, all hardware based - just move a jumper. Performance metrics between ECC and 'simulated ECC' had negligible differences.
The 8 slot model has two SATA ports. By setting a jumper, you could have the entire RAM capacity as one large drive on one SATA port or split it as two independent drives. If you splid the drive you had to have an even number of RAM sticks installed. Another jumper would dumb the interface down to SATA1 speeds rather than SATA2. Never tested that....
Did test RAID-0, however. (grin) The synthetic benchmarks don't hit this device's sweet spot - database usage. Reads are fast. Writes are just about as fast. The RAID controller really makes a difference, as my 3Ware card performed significantly faster than with the mainboard based RAID. Using a EVGA 780i mainboard, it was not crushingly faster than a trio of velociraptors.
For anyone who has installed XP, you know the wait between hitting the 'workgroup' and the first reboot? Just over two minutes. By far the fastest install I've ever done. The OS also started faster than any other disk or SSD system I've used.
The CF bay was a nifty option. The question came up - what if I want to shut my machine down overnight? You can. If you have a CF card with more capacity than your RAM, it will back up the disk image automagically. You can also push a button to back up the current 'drive image' to CF, and another to restore the image. (I was able to go back and forth from Linux and Windows very easily).
Anyhow, tis a fantastic high speed scratch disk or OS disk when write speed matters. For those of us who already maxed out RAM, this covers the gap between RAM drive sharing RAM with the mainboard and fast disk.
Re:failure mode (Score:4, Informative)
Same as any HDD - a hard shutdown. The battery pack will then start backing up the current state of the memory to a CF card, so that when power is returned to the system you can run fsck or chkdsk. If you don't have a CF card, it will keep the RAM alive for a few hours, then all is gone if power was not restored.
Re:Why are these always so expensive? (Score:4, Informative)
Intel's new SSD's have MFT-style stuff on the controllers; they have very fast random writes [blogspot.com].
In contrast, the Intel SSD does about 8,500 4kB random writes per second.
Re:I RTFA and now speculate (Score:3, Informative)
I've got one. In practice, it is. You cut power to the device, it will start making a backup using its internal battery - which lasts 3-4 hours. This is not dependent on you pushing the button to do a manual backup of the current drive image.
Re:No ECC... (Score:3, Informative)
I've got one. Registered ECC is not supported. Unregistered ECC is supported. I saw no real performance decrease in simulated vs real ECC RAM. The SATA interface seemed to be a much greater bottle neck.
Re:What I learned from the article (Score:3, Informative)
it needs about 20 minutes to transfer 16GB to backup card
That's 16 megabytes per second - if I had to guess, the bottleneck is the CF transfer rate and has nothing to do with the rest of the device.
Re:What I learned from the article (Score:4, Informative)
You're confusing bits and bytes.
Re:Great for swap and /tmp (Score:3, Informative)
IA32 can address up to 64GB with PAE.
Re:What I learned from the article (Score:3, Informative)