RedBear
Explorer
- Joined
- May 16, 2015
- Messages
- 53
I'll try to keep this simple. Basic question is: Is there any reason it may be unwise or somehow detrimental to the performance or ultimate stability of a zpool if some drives are on one SATA controller and others are on a different SATA controller?
More info:
I purchased a new ThinkServer TS440 70AQ000YUX from Amazon recently. The YUX model comes with two four-bay SATA hot-swap backplanes already installed, connected to a "RAID 500" card (a rebranded LSI 9240-8i, apparently). After a day and a half of trying umpteen different online "recipes" for cross-flashing the LSI 9240-8i, I was unable to even get any version of sas2flash, SAS2FLSH, megaCLI, or megaREC either in DOS or an EFI shell to even acknowledge that there was any LSI card installed in the machine, so I gave up and removed the card and replaced it with an IBM ServerRaid M1015 I picked up from eBay, already pre-flashed to IT mode. Seems to be working fine.
That gives me eight drives directly attached to the eight available SATA ports on the M1015, and my data storage needs are such that I really need to put a minimum of 4TB drives in all eight bays. I'm planning to use at least raidz-2. I have a second M1015 but the TS440 motherboard has only one expansion slot capable of supporting x8/x16 cards. So without investing in a SAS expander card that means if I want to add any additional SATA devices I would need to use one or more of the five onboard SATA ports on the TS440 motherboard.
There is space on the case for either a single-bay hot-swap module in the top 5.25" bay, or if I remove the optical drive I could install a three-bay hot-swap module, bringing the total number of drives in the pool to 9, 10 or 11. (I have read that it isn't recommended to go beyond 11 or 12 drives in a single zpool.) I would be moving to raidz-3 if I go to 9, 10 or 11 drives. By my calculations it's too economically inefficient to do raidz-3 with less than 9 drives.
I'm also looking at whether it makes sense to add a good fast small SSD drive (e.g., Samsung 850 Pro 128GB) to the mix as a ZIL device. Again, with the eight bays filled I would need to connect the ZIL to one of the onboard SATA ports, so even if I add no more 3.5" drives I will still be mixing SATA controllers if I add the ZIL.
So, what are the cons of having two different SATA controllers managing a single pool of devices? I mean, besides the most obvious perhaps of having two separate SATA controllers that could possibly fail, but how likely is that? Would I face the possibility of losing the entire array if one of the two controllers died? Or would it be a simple matter of replacing the motherboard and/or M1015 and having the array come right back up?
Will a speed difference (SATA-II vs SATA-III) between the two SATA controllers cause any performance degradation or reliability issues with the zpool?
I appreciate any input anyone can provide on this issue.
More info:
I purchased a new ThinkServer TS440 70AQ000YUX from Amazon recently. The YUX model comes with two four-bay SATA hot-swap backplanes already installed, connected to a "RAID 500" card (a rebranded LSI 9240-8i, apparently). After a day and a half of trying umpteen different online "recipes" for cross-flashing the LSI 9240-8i, I was unable to even get any version of sas2flash, SAS2FLSH, megaCLI, or megaREC either in DOS or an EFI shell to even acknowledge that there was any LSI card installed in the machine, so I gave up and removed the card and replaced it with an IBM ServerRaid M1015 I picked up from eBay, already pre-flashed to IT mode. Seems to be working fine.
That gives me eight drives directly attached to the eight available SATA ports on the M1015, and my data storage needs are such that I really need to put a minimum of 4TB drives in all eight bays. I'm planning to use at least raidz-2. I have a second M1015 but the TS440 motherboard has only one expansion slot capable of supporting x8/x16 cards. So without investing in a SAS expander card that means if I want to add any additional SATA devices I would need to use one or more of the five onboard SATA ports on the TS440 motherboard.
There is space on the case for either a single-bay hot-swap module in the top 5.25" bay, or if I remove the optical drive I could install a three-bay hot-swap module, bringing the total number of drives in the pool to 9, 10 or 11. (I have read that it isn't recommended to go beyond 11 or 12 drives in a single zpool.) I would be moving to raidz-3 if I go to 9, 10 or 11 drives. By my calculations it's too economically inefficient to do raidz-3 with less than 9 drives.
I'm also looking at whether it makes sense to add a good fast small SSD drive (e.g., Samsung 850 Pro 128GB) to the mix as a ZIL device. Again, with the eight bays filled I would need to connect the ZIL to one of the onboard SATA ports, so even if I add no more 3.5" drives I will still be mixing SATA controllers if I add the ZIL.
So, what are the cons of having two different SATA controllers managing a single pool of devices? I mean, besides the most obvious perhaps of having two separate SATA controllers that could possibly fail, but how likely is that? Would I face the possibility of losing the entire array if one of the two controllers died? Or would it be a simple matter of replacing the motherboard and/or M1015 and having the array come right back up?
Will a speed difference (SATA-II vs SATA-III) between the two SATA controllers cause any performance degradation or reliability issues with the zpool?
I appreciate any input anyone can provide on this issue.