[geeks] Impressive...

[Francois Dion]

On Wed, Mar 4, 2009 at 6:53 PM, Mark Benson <md.benson at gmail.com> wrote:
> On 4 Mar 2009, at 21:48, Lionel Peterson wrote:
>
>> On Mar 4, 2009, at 2:15 PM, Nadine Miller <velociraptor at gmail.com> wrote:
>>
>>> On Mar 2, 2009, at 11:58 PM, Mark Benson wrote:
>>>
>>>> I can see why they make such good NAS arrays, it's just a pitty Intel
>>>> only put 1 RAM slot on them, I'd dearly love 4GB of RAM to cache for
>>>> ZFS. Maybe I could use a Flash setup and use Johnny Schwartz's great
>>>> ideal of having Flash as your cache using all ZFS's clever algorithms
>>>> to prevent it burning out :)
>>>>
>>>> See: http://blogs.sun.com/jonathan/entry/managing_a_bestseller
>>>
>>> Maybe one of those 4 or 8GB SSD's someone's taken out of a netbook to
>>> upgrade?
>>
>> 32 Gig SATA SSDs are under $100, and sometimes 64 Gig drives are about
>> $100-125. Both are 2.5" notebook size.
>
> I noticed if you do a Solaris 10 10.08 text console install (which I did to
> get the ZFS root) and use ZFS as the file system at one of the stages it
> gives you a choice of something like 'Standard' or 'Flash'? Anyone know what
> that's about?

Flash archive. not related to flash memory, but instead a method of
installing quickly from a previously archived install. It has been a
choice for a long time now. What you probably want instead is the
separate ZIL (zfs intent log) on a mirrored pair of SSD.

> Re: the SSD yeh I'd probably go for at least a 32GB if I was gonna use it as
> a file cache on a disk array.

ZIL on ssd would probably improve your writes a ton. Also, dont go for
zraid or zraid2, go with mirroring. You loose half the capacity, but
reads are a bit faster. 4GB is probably as much as you'll ever need
for that. An L2ARC on SSD would help reads, but if you have 16GB on a
home server, I wouldn't bother with that. It makes sense only if you
have maxed your RAM and still need to improve your reads.

> As a hard drive nerd, I'm very proud of everyone's NAS arrays but I want
> half a chance of having something compact and quiet. 4 3.5"s and a 2.5" will
> suit me fine.

How are you thinking of using the 2.5"? I use 2x 3.5 for the os
(bootable zfs) and /opt and other anciliaries, and two mirrors, for 6
drives total. I used to have oracle on a clariion but zfs and sata is
faster. If I needed more write performance, I'd add a pair of SSD for
the ZIL. But even with multiple ATSC HDTV streams recording and
playing at the same time I still have plenty of wiggle room without
that, so...


> If I wanted to add the disks in stages what
> would work best from a ZFS point of view? I hate the idea of buying 4 disks
> at once, for obvious reasons...

Add them 2 at a time, mirrored. Then either append the new mirror to
the pool, or create a new pool for the new mirror. Not sure what your
application is. But do not use ZFS without redundancy.

Francois