Advances in New Western Digital Drives

An anonymous reader writes "The Western Digital Caviar SE16 WD2500KS 250 GB hard drive has 300 MB/sec transfer rate the drive has a monster 16 MB cache, both of which should make it one of the best performing 7200 RPM drives on the market. WD categorizes this drive in the "Highest Performance" section of its desktop market, so its safe to assume that is has solid performance without the expense of an enterprise level drive. With products like this available, advances are being made in the storage industry that are not being rivalled by those in other areas of computing, especially considering the price level of this drive."

Comments

This is not new or special

[Anonymous Coward]

WD released this drive at least 3 months ago, and other drives with 16mb caches have been out even longer.

This is just another useless anonymously submitted article by Sal Cangeloso that may in fact be a slashvertisement. Notice the price listing on the first page, unless of course you have your ads blocked.

Re:This is not new or special

[MoonBuggy]

Not only is it an advert, it's an incorrect one. If you want to be using an "enterprise level" drive, it's the 400GB WD4000KD you should get - same series (Caviar SE16), but the hardware is physically identical to the newest 400GB 'Raid Edition 2' from WD. The 400GB Caviar SE16 model is based on the 10k Raptor family of drives designed for maximum speed, whereas the 250GB SE16 is descended from the standard-issue Caviar family. The only place where the 250GB model beats the 400GB is the support of a 300MB/s SATA2 bus rather than the 150MB/s of SATA1, but since no drives can actually deliver anything like 150MB/s transfer, it's redundant anyway.

Note that I don't intend to advocate any one of these drives - I couldn't care less what you buy, I just want to lay out the facts properly.

Re:This is not new or special

[spatenbrau]

According to the article, the 250GB bursts hit 171 MB/s, so actually it would be hindered by SATA1.

Seeing how the overall data-rate off of the heads is only in the 60MByte/sec to 90MByte/sec range, all this talk of 300MByte channels is bordering on dishonesty with numbers. The burst rate sounds like it is simply the speed at which the on-board cache can be read at. That isn't going to a number that influences much other than artificial benchmarks.

This article is just another article from an ever growing number of "fan-boy" review sites that read like ad-copy. A real review would test the disk throughput with something similar to:

dd if=/dev/wd0c of=/dev/null bs=1m

and then note the true MBytes/sec that the disk achieved. This is the best-case number that essentially allows the disk to stream with very little track-to-track stepping. Good disks will be able to do 60MBytes/sec on the outer tracks, but will usually slow to 2/3rd's that speed on inner tracks.

Re:This is not new or special

[Shanep]

According to the article, the 250GB bursts hit 171 MB/s, so actually it would be hindered by SATA1. Burst speed isn't my #1 consideration anyways, but it's something.

Drive quoted burst speed comes from or to on drive cache anyway. That cache is good to help the drive sustain it's highest read transfer rates through read-ahead (when the OS comes back for the next block, it has already been read from disk) and also an OS can send small writes to the drive faster. But in practice this mostly just helps a disk to meet it's highest sustained transfer rates. The burst speed sounds good and 16MB cache sounds good, but in these modern times, when we use OS' which use free memory as buffer/caches, we have a LOT of memory and that memory is REALLY FAST, on-drive caches are mostly being used as buffers. As far a caching goes, they don't really get used all that much, since re-reading a block will almost always come from system RAM before it comes from drive cache RAM. Sure it is true that the read-ahead caching on the drive is caching, but in practice it is mostly used as a buffer.

Are there some other SCSI drives with higher performance now?

From a practical point of view or from a meaningless burst speed point of view due to large on-drive caches and fast busses?

I have a Fujitsu SCSI320 drive which sustains about 94MB/s at the beginning of the disk, which slowly tapers off to about 64MB/s at the end of the disk. That is faster than the raptor and this SCSI drive is also faster than the raptor in other aspects like read service times, I/O rates, etc.

There have been Fujitsu, Maxtor, Seagate and Hitachi SCSI drives faster than the raptor for a long time. The Maxtor Atlas 15K II is really fast.

In fact, as far as sustained reads and writes go, access times and sustained I/O, has SCSI EVER lost the top spot?

Re:This is not new or special

[timeOday]

The burst speed sounds good and 16MB cache sounds good, but in these modern times, when we use OS' which use free memory as buffer/caches, we have a LOT of memory and that memory is REALLY FAST, on-drive caches are mostly being used as buffers.

I've questioned the usefulness of hdd cache compared to OS main memory cache before on slashdot and gotten flamed. Unfortunately I've still never seen any benchmark that convinced me of whether large onboard cache really helps, or just helps results on benchmarks which intentionally avoid OS disk caching. If anybody has some hard info, post a link.

In fact, as far as sustained reads and writes go, access times and sustained I/O, has SCSI EVER lost the top spot?

Sure, SCSI drives always had the quickest seek (access) times. The highest RPM drives were offered only with SCSI interfaces. That's what set them apart as "server" drives. I don't think there have been any 15K SATA or PATA drives, have there?

Re:This is not new or special

[Shanep]

I've questioned the usefulness of hdd cache compared to OS main memory cache before on slashdot and gotten flamed. Unfortunately I've still never seen any benchmark that convinced me of whether large onboard cache really helps, or just helps results on benchmarks which intentionally avoid OS disk caching. If anybody has some hard info, post a link.

I don't have a link at the moment with any hard info. But I did recently test re-reading a 1GB file in FreeBSD 6.0 Release on my AMD XP2800+ with 2GB DDR ram...

came out to about 588 MB/s.

(that's 2^20 MB/s and not the bogus 10^6 MB/s.)

I might be able to dig up a link which proves that larger on-drive caches can actually hurt performance, since I did see a benchmark at Storagereview which showed this in two almost exactly the same WD drives which only differed in cache size (same model drives, except one was a "Special Edition" with larger cache only)....

Anonymous Coward posts Slashvertisement

[Yahweh Doesn't Exist]

nothing to see here.

desktop hard drives are quite possibly the most boring technology possible, except maybe non-wireless network cards. who cares?

300MB/s my arse

[Darren Winsper]

That drive uses SATA 300MB/s, which means a peak speed, not a sustained speed. It seems the drive can manage 50-60MB/s sustained.

Nice but...

[snevig]

Storage Review has the Hitachi 7K500 as the best desktop performer out there right now.

Their review of the WD2500KS compares it to the Hitachi 7K400 and the WD clearly loses out.

The 7K500 is compared to the 7K400 in its review and the next-gen performance boost is quite clear.

Re:Nice ad

[Phroggy]

We're not especially thrilled about it.