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SW RAID and sleep/wake

D

danny_w

macrumors 601
Original poster
Mar 8, 2005
4,473
305
Cumming, GA
Can the use of SW RAID cause issues with waking from sleep? See my thread at

https://forums.macrumors.com/threads/1711041/

I am wondering if having my home folder and/or iTunes folders on an external SW RAID is causing my unresponsiveness after wake. I am planning on doing some tests tonight to see what is causing the wake problem but thought somebody here might already know the answer. The ssd has a clean install of Mountain Lion 10.8.5 and the external storage consists if 3 1TB disks in a CalDigit T3 box connected via Thunderbolt to my 2012 mini.
 
I think I found the problem after the series of experiments that I listed above.

1) After moving the home folder back to the internal ssd the unresponsiveness on wake disappeared but the AppleTV would still time out when looking for the library if the computer and disk were asleep.
2) This step was not necessary since the computer itself was now responsive immediately after wake.
3) I then moved the iTunes library to another external (not RAID) and ejected and shut off the T3. This seemed to cure the AppleTV issue with timing out. I tried it again this morning after the computer and disk had been sleeping all night and again the AppleTV immediately found the library.

The conclusion that I draw from all of this is that something (the software RAID drivers most likely) takes a while to wake up and become completely responsive after waking from sleep. This is my first experience with software RAID and I think I have learned a few things:

a) Do NOT put your home folder on a software RAID volume or the computer will be unresponsive for a while upon waking from sleep.
b) Do NOT put your iTunes library on a software RAID volume or attached devices may time out while waiting to connect to the library.

Of course both of these problems could be avoided by not allowing the computer or drive to go to sleep, but that is not a solution that I want to accept at the moment. I will probably be sending the T3 back to CalDigit. I have been in discussions with them about the issues I have been having and they are interested in the outcome.

If anybody here that has experience with software RAID can shed some more light on the situation or correct my conclusions then please do so.
 
Have anyone else experienced the same issues as these? I'm trying to figure out what DAS-sollution to go for. And I also want to put the itunes library on the external disks and access it through apple TV.

There has to be other users that have put their itunes library on an external raid disk. Do you also have problems with wake up delays? Is it limited to software raid?
 
The only delays I've seen is the spin up delays of hard disks. Some take a lot longer than others. Some 4TB 5400 rpm disks, for example, can take several seconds.

I typically leave my iTunes host on 24/7 but the external disks do spin down. When I fire up the AppleTV, depending on the state of the external drives, it can take several seconds before the video begins to load. I have never seen a AppleTV timeout, however.
 
ColdCase said:
The only delays I've seen is the spin up delays of hard disks. Some take a lot longer than others. Some 4TB 5400 rpm disks, for example, can take several seconds.

I typically leave my iTunes host on 24/7 but the external disks do spin down. When I fire up the AppleTV, depending on the state of the external drives, it can take several seconds before the video begins to load. I have never seen a AppleTV timeout, however.
Click to expand...

thanks for the reply!
You leaving your itunes host on 24/7, does that mean that you're not letting it go into sleep? Because that seems to be causing the problems danny_w has.

And what DAS are you using? Software raid or hardware raid?
 
I use a USB 4TB HGST hard disk for the iTunes Library and an old 500GB Firewire drive for a couple left overs and as a scratch disk (they are both plenty fast enough to stream compressed HD video wirelessly).

The host iMac is currently set to never sleep, except for the display. I used to let it sleep, but don't bother now.

If I ever run out of space on that 4TB drive, I suspect there will be inexpensive 5 or 6 TB+ drives available.
 
CHNO-Chris said:
One solution to drives spinning down is to make sure they don't spin down :cool: - the best answer I've found to that so far is https://www.macupdate.com/app/mac/31158/keep-drive-spinning

HTH!
Click to expand...

But as far as I've understood danny_w's problem he's not having issues with the disks spinning down, but more likely issues with the thunderbolt connections timing out.

If that means that all external thunderbolt drives with raid (software? and hardware?) will have time out issues, when for example having the itunes library on them and accessing it through appleTV, I'll have to look for other sollutions.
 
dubydoo said:
If that means that all external thunderbolt drives with raid (software? and hardware?) will have time out issues, when for example having the itunes library on them and accessing it through appleTV, I'll have to look for other sollutions.
Click to expand...

I can safely say that it does not apply to "all". I have an external Thunderbolt array which powers off (the whole array, not the drives) when my Mac sleeps. When the Mac powers on, the array boots its OS and comes ready - it takes about 30 seconds. iTunes is perfectly happy with this arrangement (Apple TVs too).

n.b.: iTunes is happy, but I am not, since having "Wake for network access" means my Mac wakes up every two hours to register its services. So every two hours everything is powering up and powering down. I am not comfortable with that, so either I leave everything on (and let the drives sleep), or I turn off "Wake...".

A.
 
Last edited:
dubydoo said:
But as far as I've understood danny_w's problem he's not having issues with the disks spinning down, but more likely issues with the thunderbolt connections timing out.

If that means that all external thunderbolt drives with raid (software? and hardware?) will have time out issues, when for example having the itunes library on them and accessing it through appleTV, I'll have to look for other sollutions.
Click to expand...
Based on my experiences and tests, and reports from others, I believe that my problem was strictly a thunderbolt wake issue that for most uses would not be a problem, but manifests itself in :apple:TV timeouts when trying to wake the thunderbolt disk from sleep (iTunes on the connected Mac has no such issues because the computer must wake before iTunes becomes active). This does not mean that I have given up on thunderbolt; quite the contrary, I have (re)ordered a CalDigit T3 for my main external storage, including iTunes (I just won't let my Mac or disks sleep). I have tried several external drive arrays and I think the T3 is the best of the bunch for my use, and I'll stick with it this time. I am particularly sensitive to noise, and the T3 is the quietest multi-disk solution that I have seen. I have plenty of backups so the SW RAID 0 does not bother me at all.
 
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