5 Replies Latest reply: Feb 26, 2009 1:53 PM by DSA1
l_elephant Level 2 (375 points)
i was going to ask the question whether it was better to spend the money in a card with port multiplier tech or the enclosures with that same tech. With the very little research i did after asking myself the question, i don't see any 4+ bay enclosures without it.

So, am i wrong to assume that as long as purchases will be of 4+ bay enclosures, there is no initial need to spend extra money on a esata card with the PM tech? (i.e I see nonPM enclosures in single and 2 bay formats, but not 4+)

i was going to figure the contrary. A PM card will permit the multiplication of relatively inexpensive non-PM enclosures, thusly saving money.

so, my question finally; anyone forseeing multiple bay enclosures could initially go with a nonPM card?


well, i found one at the very least;

i guess that answers my question, except

what happens when the card and the enclosure both have PM tech?]

Message was edited by: l_elephant

MP2007, Mac OS X (10.5.5)
  • Malcolm Rayfield Level 7 (28,075 points)
    If you want to use PM, both the card and enclosure must support it. The card has to be able to handle multiple drives on one SATA cable and he enclosure needs the circuitry to connect multiple drives to one SATA connector. Note that PM enclosures can have up to five drives but the total transfer rate is limited to 3 Gbits/second (about 300 MBytes/second). With newer drives capable of 120 MBytes/second each, a PM enclosure can be slower than one with a separate SATA connection for each drive. That doesn't necessarily mean more cables, since some SATA cards and enclosures use iPass cables which handle four SATA drives per connector.

    There are also multiple drive enclosures with built-in RAID controllers that can connect to a non-PM SATA card or one of the spare SATA port on the Mac Pro logic board. The total data trasfer rate ill be limited by the single SATA connection to the same speed as with PM.
  • mbean Level 4 (1,250 points)
    Anyone forseeing multiple bay enclosures could initially go with a nonPM card?

    Most users decide to go with port multiplication "PM" as it is relatively inexpensive, reduces cable clutter (by using a single SATA cable) and can provide high performance. The SeriTek/5PM is the best 5-bay PM enclosure that I have tested based on quality, cooling and quiet operation. Using a PM enclosure requires the use of a SATA host adapter that also supports PM. You cannot use a non-PM controller with a PM enclosure as it will not be able to see all of the hard disks.


    The SeriTek/5PM can provide RAID performance as high as 240MB/sec and maintain a high level of performance even as the hard disks approach 90% full. Mac Pro compatible controllers that are a good choice for high performance configurations with the SeriTek/5PM include the Sonnet Tempo E4P which uses Disk Utility to create RAID sets and the HighPoint RR2314 which uses the HighPoint web manager to support RAID 0, 1, 5, 10, 50 and JBOD configurations.


    Using a direct connect 4/8 bay configuration (each hard disk as its own channel) can provide higher performance when the volume is empty. However, this setup is usually significantly more expensive. An 8-16 channel controller usually costs $500 to $1000 plus dual 4-bay enclosures can be another $400-500 each. Larger enclosures will be more. You can easily spend $1400-$2000 and still need to purchase hard disks.


    When you compare the cost of direct connect systems to the SeriTek/5PM matched with a Sonnet Tempo E4P or the HighPoint RR2314 you start to see the considerable price difference. The SeriTek/5PM with the E4P or RR2314 provides a high quality, quiet enclosure that keeps the hard disks cool for $700-$800. 200MB/sec performance is more than enough for most users. If not, the beauty of the SeriTek/5PM and these cards is that you can connect an additional SeriTek/5PM to the existing card if you want 400MB.sec. performance. This can be done with up to four SeriTek/5PM enclosures which provides performance as high as 700MB/sec.

    While non-PM enclosures and cards certainly exist they are usually a more expensive option. You will need to decide which option is best for your particular needs.

    Have fun!
  • kroginold Level 1 (60 points)
    MicroCenter (www.microcenter.com) lists a 4 bay Sans Digital TowerRaid enclosure that includes a PM card for $207.99. It is listed as OS X compatible. Hope this helps.
  • The hatter Level 9 (60,930 points)
    It is likely a 2-channel, 1x card, and while it can have PM, it is not for performance RAID or more than JBOD or backup drives.

    A 4x 4-channel RAID card alone should run $169+ like Highpoint or Sonnet.
  • DSA1 Level 1 (95 points)
    kroginold wrote:
    MicroCenter (www.microcenter.com) lists a 4 bay Sans Digital TowerRaid enclosure that includes a PM card for $207.99. It is listed as OS X compatible. Hope this helps.

    The drivers for that enclosure only support OS X 10.5.1 & BELOW.