msa question

[tommy_28]

I have two basic questions for MSA controller & switches,

1. for MSA500, what happen if server use a smart array card. In my compenion for common scsi card array info stores in MSA SA-642 card, not in SCSI disks right? but if I use a server side smart array, where is the arrary information, shall I config it with MSA500 or server side card?

2. for MSA1000, with internal 8 port fc switches, does both controllers have cross connection to both switches? I mean, if one controller fails, all ports connecting to the switch right back to this controller will fail?

thx & regards.

[Stephen Kebbell · Accepted solution]

Hi Tommy,

the MSA controllers (both 1000 & 500) are an extension of the Smart Array line. They all store the RAID info on the disks, thus allowing easy migration from one controller to another, e.g. can take disks that were in a server attached to an SA-5300 and move them to an MSA1000 without data loss (with everything shut down beforehand, and the disks have to be in the correct order).
A server needs a Smart Array controller (either an onboard 5i or a 532) to connect to an MSA500. You configure it via ACU on the attached server.

For the MSA1000, each controller only connects to one switch. The internal switches only have 7 external ports. The other port is internal and connects directly to corresponding MSA controller.
If a controller fails, I/O fails over the the 2nd controller, which is usually in a 2nd fabric. This means that all ports connected to the 1st switch won't see the MSA any more, so unless the hosts have a connection to the 2nd fabric (i.e. a 2nd HBA & securepath) they will lose access to the MSA storage.

Hope this helps.
Regards,
Stephen

[tommy_28]

thx for your quick help.

Thus raised another concerns:
I've checked MSA30, after raid creation I switched to another RAID card, RAID info still persists. So it turned out RAID info is in disks. My question is, where does these informations in? I've check in Linux OS there's no dedicated partition for store such information.

I used SA5i+ connecting to MSA500 and it works, while SA5302 does not work. MSA500 documents does not indicate which card is supported, this is strange hum?

SA5i+ does not store raid informations, while SA5302 does. When I move out the JBOD that attached to SA5302, it continued trying to locate these disks.

[Stephen Kebbell]

Hi,

the MSA500 does not support the SA5302 controller. Only the SA-532 and 5i. In fact, I've just noticed that there is now an MSA500 G2, which is only supported on SA-642 controllers (according to the Quickspecs).

I believe the RAID information is stored in the first few sectors of the physical disk. You will not be able to see this information directly from the OS. As far as individual disks go, only ACU will be able to see those, the OS will not see them. You create an array, then in that array you can create one or more logical drives, and the OS sees these logical drives as physical "disks".

Regards,
Stephen