I'm looking at buying a new harddrive, but can't seem to understand WD naming scheme. I see JS, YD, JD, SD, JB, etc. I have no idea which ones mean what. Why are they sometime written as "AAJS" and other times as just "JS"? Does anyone know of a website that has a quick read through? Does anyone know which of these should be avoided at all costs?

Links to the HDDs I mentioned.

http://www.newegg.com/Product/Prod [...] 6822144415 WD1600JS
http://www.newegg.com/Product/Prod [...] 6822136195 WD800AAJS

(they are both a Western Digital Caviar SE, does the AA mean anything?

I believe the "AA" series drives use a single higher-density platter, while the non-AA ones use two lower-density platters. I'm not positive on that, but I think the AA ones are later technology regardless.

SomeJoe7777 is correct - the AAJS have higer density platters. Also the AAJS support NQC and JS do not.

http://westerndigital.com/en/produ [...] anguage=en

Thanks for the link firemist, but after doing some digging and reading the benchmarks, I already found out that the YS drives are the ones to get. I already have a 7200.10 drive as my OS drive, so speed isn't a concern for me. I just need another drive for more storage space. Someone on ebay has a new 250GB YD drive for $60 shipped. I didn't know what YD meant, I guess I still don't seeing as YD isn't on that list. I guess seeing as I have my 7200.10, I shouldn't care so much. I am curious to learn more about WD drives, if anyone has any meaningful links I'd be more then happy to look at them.

AA-- = newest drives (high density, PMR)
AB-- = newest drives (high density, PMR) server edition "RE2" 1M hour MTBF
AY-- = " " 1.2M hour MTBF
-S = SATA300 interface
-D = SATA150 interface
-B = ATA100 interface
S- = 8MB cache server drives (higher MTBF) "RE"
Y- = 16MB cache server drives "RE"
B- = 2MB cache desktop drives
J- = 8MB cache desktop drives
K- = 16MB cache desktop drives

So if speed was important, I'd look for either a AAKS, or a AAYS. I already read a review on anand last night as saw the YS in action.

Thanks for the post.

Yes, any of the AA, AB, or AY drives should be what you're looking for (250, 500, and 750 especially because of the higher density platters - I believe the 160 & 320 have lower densities - 250GB/platter vs. 160GB/platter).

That is not necessarily the case. The WD WD5000AAKS and smaller are not PMR. I like how WD confuses the issue about which drives are, and are not, PMR. I think it is a seriously questionable marketing tactic. You have to go to their website and read the fine print. I suspect many people have been duped, I almost was. Maybe the "AA" means 16MB cache, but it doesn't guaranty PMR. Here is a quote from WD's website, that is linked in this post.

Bastards! I was also duped.

They almost got me. I couldn't understand why the top feature on the specs tab on Newegg for the WD7500AAKS said

And the same for the WD5000AAKS said

That didn't make sense, so I checked WD site and found the subterfuge. Even though I didn't get burned, it really pisses me off. WD should be ashamed of themselves.

So does anyone know what the AA means? I like Seagate's naming scheme. 7200.9, 7200.10, 7200.11, etc. You know what your getting. WD seems to have different letters for what seems to be the same drives. If you look at what Kyle wrote, you could have the KS and the YS both mean the same thing. (SATA 300 and 16mb cache.) Being an "RE" drive would be the only difference. If you don't know what RE means, you might think that it doesn't matter. RE drives are the performance drives however, and are worth buying. RE2 drives seem to not be performance drives, but server drives, if I remember my reading correctly. I do agree, WD should be ashamed of themselves.

RE means the higher MTBF drives suited for servers and severe 24/7 operation.

Edit: I don't believe they have any performance advantage over non-RE/RE2 drives, just greater reliability and longer warrantees.

RE or RAID Edition drives have Time Limited Error Recovery (TLER). From the WD site

http://wdc.custhelp.com/cgi-bin/wd [...] I%2A&p_li=

Western Digital manufactures desktop edition hard drives and RAID Edition hard drives. Each type of hard drive is designed to work specifically in either a desktop computer environment or on RAID controller.

If you install and use a desktop edition hard drive connected to a RAID controller, the drive may not work correctly unless jointly qualified by an enterprise OEM. This is caused by the normal error recovery procedure that a desktop edition hard drive uses.

When an error is found on a desktop edition hard drive, the drive will enter into a deep recovery cycle to attempt to repair the error, recover the data from the problematic area, and then reallocate a dedicated area to replace the problematic area. This process can take up to 2 minutes depending on the severity of the issue. Most RAID controllers allow a very short amount of time for a hard drive to recover from an error. If a hard drive takes too long to complete this process, the drive will be dropped from the RAID array. Most RAID controllers allow from 7 to 15 seconds for error recovery before dropping a hard drive from an array. Western Digital does not recommend installing desktop edition hard drives in an enterprise environment (on a RAID controller).

Western Digital RAID edition hard drives have a feature called TLER (Time Limited Error Recovery) which stops the hard drive from entering into a deep recovery cycle. The hard drive will only spend 7 seconds to attempt to recover. This means that the hard drive will not be dropped from a RAID array.

If you install a RAID edition hard drive in a desktop computer, the computer system may report more errors than a normal desktop hard drive (due to the TLER feature). Western Digital does not recommend installing RAID edition hard drives into a desktop computer environment.

I had sent a message to WD tech asking what the difference was between the WD2500KS and WD2500AAKS before I made my purchase and received no reply. Its been almost 2 weeks now since I asked them.

I went with a WD2500AAKS. I made a topic here asking what the difference was between the 2, WD2500KS and AAKS and most replys thought the AAKS was the newer better one. I hope I made the right choice. Both AAKS and KS were the same price at newegg for the OEM.

Be aware that WD drives are shipped with something called 'acoustic management' enabled. To get the full performance of the drive you have to download Hitachi's Feature Tool to disable acoustic management. The difference in noise is miniscule, the difference in performance is noticable.