Barracuda XT, Barracuda, Barracuda Green, DiamondMax and other desktop SATA and IDE drives

[Redstar5x5]

Hello All,

I have a Dell Equalogic PS6000E SAN currently populated with 16  ST3250310NS hard drives.  I want to upgrade to larger hard drives and have found the ST2000DM001.  I wanted to ask if anyone has used the ST2000DM001 for SAN, if it is different in any way other than storage space size than the ST3250310NS or if there is any reason that the ST2000DM001 wont work inside a PS6000E array.

Thanks for your time.

Brian Coss

[fzabkar]

The ST3250310NS is promoted as an enterprise class drive, whereas the ST2000DM001 is a "desktop mainstream" model. Enterprise class drives are supposedly more "robust", but I don't know whether this robustness is implemented in firmware or hardware.

AIUI, the ST3250310NS incorporates Error Recovery Control (ERC) which defines the timeouts for Read/Write commands so that the drive is not dropped from the array as a consequence of excessively lengthy read retries. I don't know whether the ST2000DM001 supports ERC. However, I do know that the 7200.11 mainstream drives supported ERC, but any settings were volatile, ie the changes did not survive a power cycle.

Another consideration may be APM. The ST2000DM001 is preprogrammed in the firmware to unload the heads after a relatively short idle time, as a power management measure. This may result in a significant delay, or even a timeout, when the drive is commanded to spin up again. As for the 7200.11, any changes to the APM settings are volatile. There seems to be some dispute as to whether the latest firmware (CC4H or CC9D) alters this behaviour.

A third consideration may be the drive activity LED. This is driven from pin #11 of the SATA power interface. The same pin also controls staggered spinup. Some firmware versions do not support the LED, but the following discussion suggests that CC4H firmware is OK:

http://lime-technology.com/forum/index.php?topic=18812.0

Still another consideration may be the number of platters. The ST2000DM001 is/was manufactured with 4, 5, or 6 heads.

http://www.users.on.net/~fzabkar/HDD/GRCC4CD9.TXT

The 4-head (2 platter) drive has a significantly faster transfer rate than the 6-head (3 platter) drive. The different versions can be identified by the first three characters of the serial number. The third character indicates the number of platters. AFAIK, a W1Exxxxx / Z1Exxxxx / S1Exxxxx drive has 2 platters whereas a W1Fxxxxx / Z1Fxxxxx / S1Fxxxxx drive has 3 platters. The following discussion demonstrates the performance difference:

http://forums.seagate.com/t5/Barracuda-XT-Barracuda-Barracuda/2TB-ST2000DM001-Barracuda-from-Seagate...

[Redstar5x5]

Wow thanks for the break down.  I appreciate it.  That is  alot of info but I think I get that your hinting towords it isnt a good idea and wont work.  Maybe I should upgrade to the ST32000645NS.  That way I get the bigger size and the enterprise class performance.

Anyone have experiance using the ST32000645NS in a Equallogic box or SAN array?