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Solid state disk drives

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Just curious if anyone knows of any inexpensive (ie < $1000) solid state disk drives that use either SCSI or ATA interfaces. Searching around on the web I've only found some fairly high end ones for enterprise purposes (prices were all over $4000 starting with 320MB drives).

Thanks!

Dan Davis

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There is no such thing thing as a cheap SSD with conventional interfaces, unfortunately. Even $4000 is dirt cheap for an SSD. The closest thing you will get for that budget is either very slow removable media or a RAM drive using existing memory (the later of the which would be a negative gain).

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Alas, there is no such animal that I am aware of. Inexpensive is an extremely relative term when used in conjunction with SSD. They just don't go together (for the moment).

The problem is that the performance gains from an SSD used with large databases or ERP systems justify the huge expense for the market they target.

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Most modern DBs are tunned to use system RAM just as well, the only gain with an SSD is lower CPU% so the market share has actually decreased from what it was as I understand.

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How much are those smartmedia drives? like the ones that use memory sticks in cameras in pda's? I know the media is priced well ...

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The smartmedia USB devices used for reading them on a desktop are roughly $20 a pop w/o S&H.

You can get it at http://www.pricewatch.com

There are a variety of options to choose from. I think there is another reader which costs around $35-40 which can read almost any type of SSE storage device apart from MMC/SD/SecureMedia.

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you can always buy standard flash (the faster varieties, like sandisk ultra) and an ide to cf adapter (cheap) from pcengines.com

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Guest russofris

Yes, there are SS HDD's available for under your priceline. They are called "ramdisks" ad run for under 1$ per meg. They aren't ATA or SCSI though.

Unfortunately, size is extremely limited (most systems have a 3-4GB ram limitation), but they are great for 2.5GB databases

Thank you for your time,

Frank Russo

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I figured as much as far as prices.

Memory cards like CF and MMC btw perform much worse than even modern 5400 RPM IDE drives. Try 11ms access times and 1-3 MB/Sec xfer rate.

Even a small (say 1GB) SSD would be nice for personal use. That is big enough to put the OS and swap space for a typical PC on the SSD.

The ones I did find that supported 320-4GB capacities were around $4000, but had access times of .3ms and sustained xfer rate of 40mb/sec and 100mb/sec burst. That particular one used a SCSI interface.

Imagine what your boot up time would be with something like that =)

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I figured as much as far as prices.

  Memory cards like CF and MMC btw perform much worse than even modern 5400 RPM IDE drives.  Try 11ms access times and 1-3 MB/Sec xfer rate.

  Even a small (say 1GB) SSD would be nice for personal use.  That is big enough to put the OS and swap space for a typical PC on the SSD.

The ones I did find that supported 320-4GB capacities were around $4000, but had access times of .3ms and sustained xfer rate of 40mb/sec and 100mb/sec burst.  That particular one used a SCSI interface.

Imagine what your boot up time would be with something like that =)

Just make sure that the SSD you used was nonvolatile (which tends to cost more).

Imagine what your system cost would be. :cry:

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Here is a price list from a press release for Platypus drives:

QikDRIVE and QikCACHE products are available now. Pricing depends on configuration and may vary according to RAM prices.

QikDRIVE2 (maximum capacity 2GB) and QikDRIVE8 (maximum capacity 8GB): As an example, suggested retail price for QikDRIVE8 with 1GB is US$3,350; US$6,000 for 2GB; and US$11,100 for 4GB.

QikCACHE2 (max. 2GB) and QikCACHE8 (max. 8GB): As an example, suggested retail price for QikCACHE8 with 1GB is US$3,200; US$5,900 for 2GB; and US$11,000 for 4GB.

Hmm. $3,200 for a 1GB drive is almost within the realm of sanity for real performance obsessed people with a bit too much money. I'm sure these things would be great for email servers though.

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I intended to resist the temptation to post on this well worn topic, but I just couldn’t help myself.

I have a really hard time understanding why I should spend $3200 on a 1GB SSD, when I could buy a motherboard and 4GB of ram for less. If we assume a $1500 price for the Tyan S4520, its price equipped with 12GB of Corsair DDR-SDRAM would be ~$6300. This is much less than what platypus wants for their 4GB drive.

If legacy considerations require a ram disk for high performance, I would certainly favor a software one, on a 3.2GB/s bus, over one strapped to a 160MB/s SCSI interface.

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Guest russofris
I intended to resist the temptation to post on this well worn topic, but I just couldn’t help myself.

I have a really hard time understanding why I should spend $3200 on a 1GB SSD, when I could buy a motherboard and 4GB of ram for less.  If we assume a $1500 price for the Tyan S4520, its price equipped with 12GB of Corsair DDR-SDRAM would be ~$6300.  This is much less than what platypus wants for their 4GB drive.

If legacy considerations require a ram disk for high performance, I would certainly favor a software one, on a 3.2GB/s bus, over one strapped to a 160MB/s SCSI interface.

I used to have a P-100 with 128 MB that would boot, create a ramdisk "D:" and copy a Win3.11 image to the 64MB DrDos ramdisk.

I ran the OS from a ramdisk!!!

Was funny, but not practical.

Thank you for your time,

Frank Russo

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RAM Disk software is not the same as SSD. SSD's keep the data after you turn off the power, just like a hard disk. Such devices would need to be made up of very fast flash memory or similar technology.

Lots of uses for this. Instant boot-ups. On a linux box, very fast kernel compiles and subsequent reboots. SSD based swap space.

Magnetic RAM (MRAM) is coming out next year, and may be just the thing to make SSD's a reality.

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Very fast flash?

I am afraid that this is a contradiction in terms. NOR flash may be read at reasonable speeds, with Micron’s Syncflash among the fastest. Write performance however, is absolutely terrible.

NAND flash is offers better write performance, but its read performance is poor.

All types of flash are limited to a fixed number of writes, after which the device is worn out. This tends to be roughly 100,000 writes for most devices, except for those offered by AMD which will tolerate 1,000,000 writes. Some devices are limited to 10,000 writes or less.

High performance solid state disks using externally powered, or battery backed ram have been available for decades. On the other hand, most modern systems can be configured to power SDRAM from standby power. Either way, the solid state disk must be backed up with regularity.

Since I tend to boot only once every several months, I fail to see why I would spend $11,000 to boot one minute faster. Compiles will be much faster with a 3.2GB/s software SSD, than a 110MB/s one.

SSD based swap space? This is the biggest joke of all. You will be much better off with additional physical ram, than mucking around with interrupts and driver code.

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Guest russofris
RAM Disk software is not the same as SSD.  SSD's keep the data after you turn off the power, just like a hard disk.  Such devices would need to be made up of very fast flash memory or similar technology.

That's wonderful for systems that get turned on and off a lot. "Servers" do not get turned on and off a lot. Either do workstations. The only possibility that I can think of where a SSD would be advantageous is a satelite, or some other application that experiences scenarios beyond the environmental tollerances of modern HDD's. I use a ramdisk in my liquid hybrid rocket for example.

Lots of uses for this.  Instant boot-ups.  On a linux box, very fast kernel compiles and subsequent reboots.  SSD based swap space.  

Instant boot ups? No, an Instant boot up is where the memory is paged to the SSD. Running the normal boot procedure for Linux from a SSD takes almost as long as it does from a HDD. Resolving a DHCP address will still take a couple seconds regardless of the storage subsystem. Suspend to disk is an example of "instant" boot.

Magnetic RAM (MRAM) is coming out next year, and may be just the thing to make SSD's a reality.

SSD's are a reality, they are simply too slow, expensive, and do not offer any advantages over HDD's.

Back to ramdisks....

1: Servers should rarely reboot... Ramdisks lend themselves to this environment. Using a SSD for the boot drive would be a waste of money and a misappropriation of resources.

2: Servers need high transfer rates... Ramdisks, not SSD's

3: Servers need low latency.... Ramdisks beat SSD's hands down

The only limiting factor of of ramdisks is size. Currently (for servers) it is rare to be able to have more than 32GB of ram. If you need speedy access to a 10GB DB, a ramdisk is just the thing. MS's UU/GUID/Passport system is a shining example of this (Is passport using HDD's now?)

Thank you for your time,

Frank Russo

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Okay, a few things should be pointed out here.

1) Not all SSDs are nonvolatile.

They come in both volatile and nonvolatile flavors. The ones which are nonvolatile use various methods such as lazy-writing to an internal HDD, using batteries to keep the memory powered up if there is a power fault, etc.

2) SSDs are very good at reducing seek and latency times, since there are no moving parts.

Since an SSD is made up of memory, access time is about 1000 times faster than accessing a HDD.

3) Good SSDs have no problem saturating any interface that is slower than about 100 MB/s, depending on the SSD.

This means that your system will, if you've designed things properly, be capable of pushing many more I/Os per second through.

4) SSDs completely eliminate any difference between sequential and random I/O.

There is no performance difference between random I/O and sequential I/O when using a SSD. For certain applications where it might be difficult to characterize whether the typical access pattern will be random or sequential, this is definitely a benefit (such as a system hosting both file services, web services, a mail server, and a SQL DB).

Now, what all this means is that SSDs can be quite useful and practical in certain types of applications.

For instance, if your DB server is bottlenecked because your transaction log is I/O limited, then you can dramatically increase performance by using a SSD and moving the transaction logs to the SSD. You can't achieve the same thing by adding RAM, since the data must be committed to disk at some point and that will limit your throughput. If your entire DB, including indexes, will fit on the SSD, then that would perform even better.

Another application might be if you use very large RAID arrays (meaning hundreds of disks). To minimize your window of vulnerability during a drive failure you might choose to use a SSD as your hot spare disk to minimize the rebuild time, then have the SSD mirrored to a standard HDD when you are ready to replace the HDD.

Anyway, the main point I'm trying to make here is that SSDs do indeed have their uses. Those uses just typically involve business processes to get a decent enough ROI to justify the cost.

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Indeed, you have successfully made the argument that a ram based SSD is faster than a magnetic disk, but it remains much slower than system ram.

Your point about committing to disk is a valid one, and is an example of the type of legacy consideration I mentioned above. In such a case, a simple driver can be used to create a ramdisk from system ram. I have used ramdisks under w2k for large platform builder(win ce) compiles, and the improvement is dramatic on SMP machines.

What has not been presented is an argument to use a slow, expensive, external SSD over traditional system ram.

It is true, that modern x86 processors are limited to 36 address lines, and may only address 64GB of space. It is also true, that motherboards equipped with chipsets that actually accommodate 64GB of ram, are expensive.

That said, these factors should be considered in context. For less than the price of a 4GB SSD, I can build an entire quad processor system equipped with 12GB of RAM. While this approach does limit you to a 64GB ‘disk’, I suspect the market share of > 60GB SSDs in miniscule.

If 64GB is really not enough, Hammer is right around the corner.

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Guest russofris
Your point about committing to disk is a valid one, and is an example of the type of legacy consideration I mentioned above.

Why can't you commit to a ramdisk?

Just curious,

Frank

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You can commit to a ramdisk. You can’t commit(directly) to system ram. Although modern operating systems will buffer writes, they will try to flush those buffers fairly quickly to prevent data loss in case of power failure.

When building a Window CE image for example, thousands of files may need to be compiled. Although the source files may all fit in my system cache, the compiler and linker want the output files (.obj, .dll, .exe) on disk. This can quickly become the bottleneck in a build with fast or multiple processors.

If you install a ramdisk driver, the system will flush the cache by copying to ram, rather than writing to disk.

This tends to be more of an issue with relatively unsophisticated stdio, or memory mapped programs. Serious IO bound applications designed to run on machines with large amounts of physical ram, will typically use unbuffered scatter-gather IO.

In most cases, this will obviate the need for a ramdisk.

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Ok, gloves are off.

I am generally dismayed, although not shocked, by the lack of knowledge here.

First off, what is the first thing you usually do after installing a new kernel on a recompile in linux, or any version of unix? REBOOT.

Second, what do you usually have to do to an NT box if you install, or in some cases change, services? REBOOT.

Does a RAMDISK make your computer boot faster? NO. ITS SLOWER BECAUSE THE RAMDISK HAS TO BE LOADED.

If you have infinte RAM on your PC, will it still use your disk bound swap space? YES

When you link and compile a C program on any system, will it go to disk and read your object files, libraries, and source code and make intensive use of your disk? YES Is this access sequetial or random? RANDOM.

Will an SSD with 100Mb/Sec xfer rate regarless of type of access and an access time of .03ms (yes point - zero - three, from specs on some of the SSD drives ive seen) be faster than a 15k rpm 3.8ms access Cheetah with a xfer rate between 28 and 56 mb/sec? HELL YES, ESPECIALLY ON PROGRAM COMPILES.

The original post was simply asking if any of these such devices had come down to a price point that was reasonable in my estimation (<$1000) and might be worthwhile if you are doing something like, say, developing software on your at a rate of $80/hour. I was not asking if this was reasonable for some teenager playing Quake.

People make the *bad* assumption that what they use their PCs for is what everyone else uses them for, or that their idea of 'justified expense' is the same for all cases. It is not.

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I am generally dismayed, although not shocked, by the lack of knowledge here.

Yeah, it sure would be helpful if there was someone around who had developed both the hardware and the firmware for a solid state disk.

It would be even better if that person had written ramdisk drivers for multiple operating systems.

I guess we will just have to make do with what we have.

As I have conceded above, an externally powered SSD will probably shave as much as a minute off your reboot time. A BIOS change would allow you to do the same thing with a standard Suspend To Ram motherboard, but I will admit that this isn’t something laymen are going to attempt.

If you reboot every single day, you are now 0.069% more productive.

As far as the use of a paging or swapfile is concerned, this depends on the operating system you are using, and how it is configured. For example, there is no page file in my system.

If you are struggling to understand how paging or swapping works, you may want to read part of this thread.

As I described in my post, building large projects with conventional tools, does benefit from a ramdisk.

Now a question for you:

Will a ramdisk with 3.2GB/s xfer rate [regardless] of type of access and an access time of 0.000015ms (yes point – zero – zero – zero – zero – one – five, from specs on some of the system ram I have seen) be faster than a 0.03ms access external SSD with a xfer rate between 110 and 160 mb/sec? HELL YES, ESPECIALLY ON PROGRAM COMPILES.

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i responded because i thought you just wanted something ultra-reliable to run on a router-like pc

cas is totally right - buying ssds is asinine when compared with the ramdisk option. take a piss while your system boots and do your kernel compiles (how many of these you do per day?) on a ramdisk. there's no way you reboot often enough to make it worth your money, and the system you could buy with that money would no doubt be faster than what you've got and infinitely more resellable than a ssd.

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