Switch to full style
User discussion and information resource forum for BootIt Bare Metal.
Forum rules
Post a reply

SSD alignment headaches

Wed Dec 21, 2011 1:53 pm

I acquired a 120GB SSD for my laptop, as a *secondary* drive. My laptop supports two. I belatedly learned that the secondary channel is allegedly SATA I (1.5Gbps), but since I'm getting ATTO benchmark write/read results of 245 and 275MBps @ 8192, that doesn't seem to be true. Even though I installed it as a secondary drive, I had every intention of booting from it. The reason I did it is to maintain UEFI BIOS support for the mfr. diagnostics and recovery partitions, which I'm betting MUST be located on the primary disk, and possibly in specific MBR locations, in order to be accessible. I really didn't want to squander 25GB of the SSD on those partitions, so I devised an alternative: I moved the Windows system reserved partition to the SSD, then split the Windows boot partition and copied the essential half to the SSD, and finally edited the BCD store on the system reserved partition to point to it. After the move, the second half of the Windows partition, the 'data' half, was expanded to fill the entire space remaining on the original drive. I used the Windows 'Location' feature to point to the special folders on this partition, and for user Public and some other folders I created junctions or symlinks in their former locations.

All that worked fine, insofar as Windows booted as if nothing had happened. The problem is that NONE of the partitions on the SSD came out aligned! The recovery and diagnostic partitions on the platter drive remained aligned, and so was the expanded (logical) data partition. I knew I needed to correct the SSD alignments, lest it impact performance and wear; I was only getting a 6.1 WEI disk score, which seemed a bit low.

Since BIBM supposedly supports and ensures alignment, I figured simply resizing and sliding each partition would fix that. It didn't!

Next I got a copy of Paragon's alignment tool. It recognized the misalignments and offered to align them, but it only succeeded on the system reserved partition! It quietly gave up on the Windows boot and BIBM partitions, reporting the result simply as "Not Aligned" with no explanation or error. It did this regardless whether I booted from the Windows partition on the SSD or from a live CD when running the tool.

FINALLY, after countless hours of trial and error over two days, using an external eSATA GPT RAID 5 enclosure for support, and including a wasted detour with Paragon's SSD migration tool, I finally succeeded in moving a copy of the Windows partition to the SSD that came out aligned. STILL the little 7MB BIBM partition is incorrectly aligned, but hopefully that doesn't matter or affect wear or performance.

My objective here is to ask: why was this so hard? Why wasn't it 'automatic'? Shouldn't there be a Sector Align menu function for partitions, if it's going to be this unintuitive?

I'd also like to clarify whether the Image For DOS component supports sector alignment or not.

Re: SSD alignment headaches

Wed Dec 21, 2011 6:44 pm

In BIBM Settings, did you choose Align at 2048?

Re: SSD alignment headaches

Wed Dec 21, 2011 9:57 pm

I did eventually enable 2048 alignment as a global default at some point, but I had thought I had read earlier that it was the default. It certainly should have been, at least for the SSD; it should have been detected as such and necessary adjustments made. Really the moment Windows 7 is in play that should be the default, right? The resulting-action table under Align on Cylinder in the manual had me thinking that: the table said that both disabled would result in 2048 alignment if there was an existing partition aligned that way, and there was... all three partitions on the original drive were 2048 aligned, and I reasonably thought that alignment would be preserved when any of them were copied to the SSD. I guess I was wrong to think that, but I shouldn't have been, should I? If a partition is 2048-aligned on a drive, when would you ever not want that alignment preserved when it's copied to another? It's not what I would call intuitive.

Enabling 2048 alignment as a global default didn't even seem to be the ultimate cure, because it wasn't until much later that the alignment problem seemed to be resolved, having no coincidence to the act of setting it.

It was all made more frustrating because I was having a hard time determining what the alignments actually were. Trying to use diskpart to do it is misleading, because it rounds off offset values in MB and GB for all but the first partition. Trying to use the WD/Acronis tool just to determine alignment (figures it wouldn't operate on non-WD drives) is apparently also misleading: it still reports two of them as unaligned now but then at the end declares them all aligned and nothing need be done, and it was doing that right from the beginning. Trying to use the Paragon tool was equally problematic, because it quietly failed to align partitions that it claimed were not; was it mis-reporting the alignment, too? BootIt Bare Metal doesn't report current alignments at all, at least not in that specific context, nor does it have a function to realign partitions a certain way that aren't. Was I supposed to figure it out from the MBR table? Maybe that would've been better than trying to use diskpart? How was I supposed to know with clarity what the alignments were when I was getting conflicting information or no information?

Re: SSD alignment headaches

Wed Dec 21, 2011 11:31 pm

You can calculate your alignment from LBA Information in Partition Properties.

I'm not sure why you had issues. I've always got the alignment I expected. BIBM and IFD.

Re: SSD alignment headaches

Thu Dec 22, 2011 12:10 am

You just enable the global option Align 2048 in settings, then copy over the
partitions. You can resize them if you want the end to be aligned too, but
that doesn't matter. If you used IFD to copy the entire drive, you'd need
to use the "aligned copy" option to realign to the new alignment. To fix
existing partitions, you'd have to slide them (then resize if you want the
ends aligned too - you may have to resize first if there is no gap to align
to). A blank drive won't default to 2048 alignment unless you have that
setting the default.

"macraig" wrote in message news:909@public.bootitbm...

Post a reply