On Nov 9, 2011, at 6:08 PM, Francois Dion wrote:

> Some laptops have pc card and expresscard slots, and you can get an adapter 
> for sd card, so you could set up your os non mirrored and just set up home on 
> a pair of sd cards. Something like
> http://www.amazon.com/Sandisk-SDAD109A11-Digital-Card-Express/dp/B000W3QLLW
> I've done this in the past, variations of this, including using a partition 
> and a usb stick:

SDcard is suitable for boot *only* if it is connected via USB.  While the 
drivers I wrote for SDHCI work fine for using media, you can't boot off it 
generally -- usually the laptop BIOS simply lacks the support needed to see 

It used to be that CompactFlash was a preferred option, but I think CF is 
falling out of favor these days.

        - Garrett

> http://solarisdesktop.blogspot.com/2007/02/stick-to-zfs-or-laptop-with-mirrored.html
> Wow, where did the time go, that was almost 5 years ago...
> Anyway, i pretty much ditched carrying the laptop, the current one i have is 
> too heavy (m4400). But it does run really nicely sol11 and openindiana. The 
> m4400 is set up with 2 drives, not mirrored. I'm tempted to put a sandforce 
> based ssd for faster booting and better zfs perf for demos. Then i have an 
> sdcard and expresscard adapter for sd. This gives me 16gb mirrored for my 
> documents, which is plenty. 
> Francois
> Sent from my iPad
> On Nov 8, 2011, at 12:05 PM, Jim Klimov <jimkli...@cos.ru> wrote:
>> Hello all,
>> I am thinking about a new laptop. I see that there are
>> a number of higher-performance models (incidenatlly, they
>> are also marketed as "gamer" ones) which offer two SATA
>> 2.5" bays and an SD flash card slot. Vendors usually
>> position the two-HDD bay part as either "get lots of
>> capacity with RAID0 over two HDDs, or get some capacity
>> and some performance by mixing one HDD with one SSD".
>> Some vendors go as far as suggesting a highest performance
>> with RAID0 over two SSDs.
>> Now, if I were to use this for work with ZFS on an
>> OpenSolaris-descendant OS, and I like my data enough
>> to want it mirrored, but still I want an SSD performance
>> boost (i.e. to run VMs in real-time), I seem to have
>> a number of options:
>> 1) Use a ZFS mirror of two SSDs
>>  - seems too pricey
>> 2) Use a HDD with redundant data (copies=2 or mirroring
>>  over two partitions), and an SSD for L2ARC (+maybe ZIL)
>>  - possible unreliability if the only HDD breaks
>> 3) Use a ZFS mirror of two HDDs
>>  - lowest performance
>> 4) Use a ZFS mirror of two HDDs and an SD card for L2ARC.
>>  Perhaps add another "built-in flash card" with PCMCIA
>>  adapters for CF, etc.
>> Now, there is a couple of question points for me here.
>> One was raised in my recent questions about CF ports in a
>> Thumper. The general reply was that even high-performance
>> CF cards are aimed for "linear" RW patterns and may be
>> slower than HDDs for random access needed as L2ARCs, so
>> flash cards may actually lower the system performance.
>> I wonder if the same is the case with SD cards, and/or
>> if anyone encountered (and can advise) some CF/SD cards
>> with good random access performance (better than HDD
>> random IOPS). Perhaps an extra IO path can be beneficial
>> even if random performances are on the same scale - HDDs
>> would have less work anyway and can perform better with
>> their other tasks?
>> On another hand, how would current ZFS behave if someone
>> ejects an L2ARC device (flash card) and replaces it with
>> another unsuspecting card, i.e. one from a photo camera?
>> Would ZFS automatically replace the L2ARC device and
>> kill the photos, or would the cache be disabled with
>> no fatal implication for the pools nor for the other
>> card? Ultimately, when the ex-L2ARC card gets plugged
>> back in, would ZFS automagically attach it as the cache
>> device, or does this have to be done manually?
>> Second question regards single-HDD reliability: I can
>> do ZFS mirroring over two partitions/slices, or I can
>> configure "copies=2" for the datasets. Either way I
>> think I can get protection from bad blocks of whatever
>> nature, as long as the spindle spins. Can these two
>> methods be considered equivalent, or is one preferred
>> (and for what reason)?
>> Also, how do other list readers place and solve their
>> preferences with their OpenSolaris-based laptops? ;)
>> Thanks,
>> //Jim Klimov
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