Improving disk performance

[keith_leitch]

I have been looking into improving my disk performance for those times when it is under load. BigMoose told me about enabling AHCI mode on SATA drives, but I can't seem to determine how to do that...there doesn't seem to be any such mode in my BIOS. Perhaps it is a 64-bit protocol and XP has it locked out (although the BIOS should still show it).

In addition: I have a spare Gig or so of memory, and could very cheaply have 5. I have been considering installing either a large disk cache in that space or a RAM disk to take up Live TV buffering (or possibly both). Does anyone have any opinions or experiences about this? The RAM disk could also be the location for the Windows Swap file.

Regarding the Live TV buffer: What happens if the allocated volume runs out of space? Does the buffer clear and reset, or does it cause problems?

[pBS]

ahci is only on certain motherboard chipsets..typically newer intel mb's...
no ahci in bios, no ahci...unless it's in a secondary rom bios that comes after main bios launch..[looks like a second bios screen with hotkey to configure]
secondary bios usually on addon cards, but some are built into bios as separate raid chip..
check mainboard manual for ahci compatibility..
you may have to re-install windows to use it as it organizes data differently on disk and needs drivers to boot from ["press F6 to load scsi drivers" at beginning of install cd boot]

secondly, the ram disk thing isn't that good an idea...tried it and there's little gain and you will run out of space if you record anything while watching tv...[hit record while in livetv]
as that stuff gets recorded to tv buffer dir instead of recordings dir and will stay there afterwards...getting erased when ramdisk is cleared..
i typically can't get away with less than 25 gigs of livetv buffer without problems..
just adding the ram will let windows use most of it for disk cache anyways, as that what windows does with memory when nothing's using it..

now moving livetv buffer to a different drive *will* help...it wont interfere with recordings drive, nor fragment it when doing 2 at once..

I keep windows on it's own partition[20g],
with gbpvr alone on secondary partition of same drive [4gig], [never gets fragmented and no virtual store/sharing problems]
then livetv buffer on third partition on same drive[24g], [quarantines it from fragmenting other drives]
then recordings on a second [and third,by magic] drive altogether[1 tb]..all ntfs for various reasons..[using ntfs links to record to 2 drives at once]

keeps drives less fragmented and data protected from eachother..and allows many recordings at once as they will record to different drives, multitasking..
ramdisk is only slightly more beneficial when using it for gbpvr only, tho a good disk cache seems to smooth out rough churning during busy periods...tho effect is negligible..
if livetv buffering is a problem, it's likely other bottlenecks or recording would also suffer same problems...[they're essentially the same]

oh and to use more than 3 gigs you'll have to use 64bit os...

[Reddwarf]

Some time ago I had problems when Comskip kicked in while another recording was going on, harddisk was absolutly choked. The problem completly vanished when I replaced my old SATA drive with a striped RAID array. The boost in performance was just unbeleivable. Now I have two raid arrays, one for windows, programs and archive and one for recordings.

And yes, It's a very good idea to keep windows and programs on it's own partition and also to allocale a fixed size pagefile/swapfile with sufficient size.

If you can, place the swapfile at the beginning of the disk (physical) because the drive reads and writes much faster on the innermost tracks (beginning of logical storage, provided the windows partition is the first on the drive, which it always should be).

Good luck

[keith_leitch]

ahci is only on certain motherboard chipsets..typically newer intel mb's...

I actually found it as I was rooting around trying to save my doomed hard drive.

["press F6 to load scsi drivers" at beginning of install cd boot]

So it's SCSI drivers that make it all happen for SATA? I'm not sure I understand. Since I am doomed to reinstall Windows no matter what, doing this on an install should not be a problem.

just adding the ram will let windows use most of it for disk cache anyways, as that what windows does with memory when nothing's using it..

But adding RAM beyond 3.5 Gig is hopeless in XP 32, isn't it? Some of the third-party disk cachers and ram disks will use that lost space, as well as the space occupied by the addresses of onboard video ram. I'm trying to find something useful to do with them. Maybe the swap file?

then livetv buffer on third partition on same drive[24g], [quarantines it from fragmenting other drives]..

But, wouldn't this just cause the same access conflicts with head seeks? I was thinking of a third drive for the Live TV buffer, onto which I would only put "simple" data that I would never access at the same time, like pictures and music.

then recordings on a second [and third,by magic] drive altogether[1 tb]..all ntfs for various reasons..[using ntfs links to record to 2 drives at once]

Again, I don't understand. Is this like a RAID controller?

oh and to use more than 3 gigs you'll have to use 64bit os...

Right, and I can't do that because I need the legacy software for a lot of what I'm doing...thus the cache or RAM disk (although I will abandon any plans for the latter, at least.)

Live TV buffering has never been a problem in and of itself, but I just want to tweak system performance when I reinstall properly. However, I am now in an urgent situation, so I guess "reinstalling properly" just ain't gonna happen.

[keith_leitch]

If you can, place the swapfile at the beginning of the disk (physical) because the drive reads and writes much faster on the innermost tracks (beginning of logical storage, provided the windows partition is the first on the drive, which it always should be).

So, you're saying the same disk as Windows? That seems counter-intuitive. Wouldn't it be better to use a dedicated or low-access drive for the swap file? I realise that putting it on the same drive as Recordings would be a mistake.

[keith_leitch]

I have three choices: IDE, RAID and AHCI. I think you were saying that RAID is my best option, but I don't really understand what you are doing. My understanding was always that RAID controllers maintain an array of disk drives that can either mirror each other or "share the load" as a single virtual drive. Is that what you mean?

Otherwise, does anyone know if setting the devices to AHCI will prevent me from reading my data disk (which was previously set to IDE mode due to my ignorance).

Actually, I'm getting the sinking feeling that XP 32 might prevent the use of either RAID or AHCI. I've been reading about the need for hardware specific drivers (oh! drivers!) On the other hand, there's a folder on the motherboard's driver disk called RAID and AHCI_SETUP. Is any of this going to mess up my existing data drive, which I have been abusing in IDE mode?

I am going to take a much-needed shower. Any opinions would be greatly welcomed.

[pBS]

yea, windows doesn't actually use much disk time for pvr use...nor gbpvr...
you only need to separate recordings/livetv buffer as only they will get heavy use...
i just keep windows and gbpvr separate for fragmentation and security reasons..
[and ability to image windows drive separate from gbpvr]

swap won't be in play at all unless mem is really low...sure windows will populate swap but it won't use it from there unless that's all that's left..so normally it never gets touched..
[at least with 2 gigs or more]

you can run legacy apps on x64 machines..32bit is emulated...
only drivers must be 64bit..

ahci driver is only *like* a scsi driver to windows...they are treated same..have to be slipstreamed into windows or loaded from floppy at cd install boot...
windows has to be able to talk to the drive before it can load windows on it..

ntfs links are like shortcuts to directories...only nothing knows the difference..
[see link in my sig]
so i can link a series dir to another drive so it will always record that series to another drive..but to all programs it will appear to be on main recordings drive/dir...

on ram, windows plus gbpvr shouldn't use much more than around a gig...
huge amounts of cache have diminishing returns...mine shows 70megs and does fine..
i've used the ram disks, 3rd party caches and most don't offer any real world improvement, only caching helps a bit, and not much needed at that...
64-128 megs cache should be enough even with other utils...

usually it's the drives performance that makes the most difference...32 megs cache on drive helps better than ram caches...and only get 7200rpm..
some drives are much much faster than others on big files like these...you'd be surprised testing actual real world sequential transfer speeds...
i've seen near 50% better perf. on same spec drives from diff. manufacturers..

[pBS]

yep, gotta re-install if going to ahci...if you want the benefits on the data drives, those too...
have to backup and reformat them in ahci mode...
it *should/ be able to read the data disks wo/reformat, but they won't get the benefits of ahci.
the data drives are the ones that need the benefits for multi-recording...
[not that the windows drive wouldn't benefit]

and be careful about raid..you can end up losing everything if you don't know what you're doing..
i've seen too many fail miserably and i won't trust a raid setup unless i do a test fail/restore beforehand..
raid can get rather complicated..
twice the speed with twice the risk of data loss, despite it's mirroring nature..
[only raid 5/10 offer real speed without risk, requiring 5 or more drives...]

[keith_leitch]

yep, gotta re-install if going to ahci...if you want the benefits on the data drives, those too...
have to backup and reformat them in ahci mode...
it *should/ be able to read the data disks wo/reformat, but they won't get the benefits of ahci.
the data drives are the ones that need the benefits for multi-recording...
[not that the windows drive wouldn't benefit]

and be careful about raid..you can end up losing everything if you don't know what you're doing..
i've seen too many fail miserably and i won't trust a raid setup unless i do a test fail/restore beforehand..
raid can get rather complicated..
twice the speed with twice the risk of data loss, despite it's mirroring nature..
[only raid 5/10 offer real speed without risk, requiring 5 or more drives...]

OK, I understand...so it sounds like I should try AHCI, since I have to reinstall the Windows drive anyway, then just live with IDE speeds on the data drive until I get a chance to back it up/reformat it/restore it. Does that sound right to you, or should I just install in IDE for now until the data backup is complete?

On your advice, I will not risk RAID. My understanding of it has always been shaky at best (never understood how spreading sectors of the same file across two disks could possibly be a good thing).

[stustunz]

what with worrying about drive speed performance
what else are you using the machine for ?