Question to the Storage Advisors: What are the practical limitations on the number of disks in a RAID-5 set? I understand that a larger number of disks worsens the probabilities of bad things like a failure or paying the worst possible seek/delay cost in random accesses. Do you have any mathematical models for evaluating these penalties? …

I wanted to let you fine folks know that I’ve recorded a few webinars on many of the topics that I routinely discuss here in this blog. Each one is about 15 minutes long and comes with smorgasbord of tasty slides. The biggest downside is that my delivery is only slightly better than Ben Stein discussing the Hawley-Smoot Tariff Act. (Anyone? Anyone?) …

Question to the Storage Advisors: Which is better: (a) backup battery for cache as found on OEM RAID controllers or (b) writing cache content to one or more disk drives?

Question to the Storage Advisors: I have several large SCSI arrays ranging in size from 600 GB to almost 2 TB. They add up to about 4.5 TB in total. They are currently seen as separate drives in Windows 2003 server R2. I’d like to find an adapter card that will let me span them so they appear as one large array. I’d rather not span them using disk manager in Windows 2003.

Question to the Storage Advisors: The age old question…RAID 5 vs. RAID 0+1 with a twist on spindles. Here’s the deal: Multiple Progress databases. Much more read intensive that write intensive. Which is faster: (2) RAID0 sets of 4 disks that are then mirrored (8 disks total) OR all 8 disks in a RAID5 config? I’m trying to figure out if more disk spindles outperforms less spindles without the RAID5 overhead.

Question to the Storage Advisors: We’re buying 2 cages that use a PCIe interface and 24 146G 15K drives. We’re going to use RAID 10. Each cage only holds 12 drives. We’ll be using 2 spares in each cage. So that’s a stripe of 5 disk groups. At 175 IOPs that’s approx 875 IOPs across the stripe. If we go higher than 875 IOPs we begin seeing higher queue lengths correct? Both cages are hooked to the same server thru the PCIe controller that supports up to 8Gb/s. This is for an Oracle db, and will host 4 dbs. 2 dbs are IO intensive, 2 are not. Right now we plan on separating the 2 IO intensive dbs to 1 cage each. Would it be better to use both cages per db? I don’t think you can stripe disks across cages(?), so would it be better to create two stripes and put datafiles from both dbs on both cages so that we effectively use 2 stripes of 5 disk groups?

Question to the Storage Advisors: How many disk IOs does it take to write one file? I have a RAID10 array writing a 120KB file. Is this one IO for the entire file, or is it one IO per sector on the disk/write cache (which would then be approx 240 IOs)?…

Question to the Storage Advisors: I just wonder, what kind of storage solution that can saturate 10Gb Ethernet backbone. If I assume I have a file server (of course equipped with 10GbE NIC on PCI-E 8x), can an external SAS/SATA-II JBOD box (using 4xwide SAS link) produce enough throughput (taking into account the hard disk speed and the link bandwidth) to saturate the network? If not, where will be the bottleneck?…

Question to the Storage Advisors: I’ve heard great things about SATA based DASD and JBOD devicess. I’ve found tons of information about the data transfer rate, but haven’t been able to find any hard data on how many sustained and bursted IOPS such systems can handle…

Question to the Storage Advisors: For network storage which is better: SATA 150 or SCSI ultra360. Balance size cost and speed. We need a terabyte for live data running and storage…