zfs discuss - Dec 2007 - Does ZFS handle a SATA II " port multiplier " ?

Anyone tried to use ZFS  with this type of box  ? . The new thing about this one
is that
   it contains a    1x eSATA  to 4x SATA Port multipler 


http://www.stardom.com.tw/sohotank%20st5610-4s-sb2.htm

  //Lars
 
 
This message posted from opensolaris.org

Lars Tunkrans wrote:
> Anyone tried to use ZFS  with this type of box  ? . The new thing about
this one is that
>    it contains a    1x eSATA  to 4x SATA Port multipler 
>
>
> http://www.stardom.com.tw/sohotank%20st5610-4s-sb2.htm
>   
There won''t be a ZFS issue; ZFS talks to any kind of Solaris block 
device, right?  The question is, will Solaris handle this concept, and 
this particular implementation.

I''m interested in the same question.  I''m looking at what to
use for
backup from my Solaris file server.  I''ve had rather bad experiences 
with external Firewire and USB disks, especially in performance (can''t 
be absolutely sure the problem isn''t with Windows there, though, or
even
the specific backup software).  So I''m wondering if using the eSATA
port
to connect to an external enclosure with multiple drives in it might be 
a winning strategy.  Two external enclosures, alternate monthly for a 
full backup, say.  I''m tempted to use ZFS on a random selection of
disks
with no redundancy, as a way to keep costs down. This does of course 
multiply the chance of a drive going bad and invalidating a big chunk of 
the backup just when it hurts most.

I''ve also considered buying two Drobos for this, but as a USB device I 
think of it as painfully slow.  But it would let me stick my spare 
drives into it in random combinations and give me redundant protection 
on my backups.  If I were using a single drive, I''d accept the risk of 
it failing, but when I''m using three or four drives, I''m not
so sanguine
about it.  I could buy two 750GB external drives and just back up to 
those, for a while longer (and then presumably move those drives into 
the server, and get something even bigger for the backup drives; but in 
the long run I don''t think it''s smart for me to count on
always using a
single drive for each backup).

Tape drives and tapes seem to be just too expensive.  Am I out of date 
here?  What would I need to buy to back up a system that currently has 
about 600GB of data in it, growing a few GB a month on average?  
(Digital photos; not as bad as if I were recording HD video, but still 
pretty bad at about 9MB a shot for the camera originals).

Also, what *software* does one use?  For a full, and for an 
incremental?  One obvious idea is to just cp -a to the drive for a full 
backup.  This leaves each file easily findable and individually 
accessible, which is good.  ZFS can give me a view equivalent to an 
incremental, can''t it?  Which I could then copy somewhere suitable?

-- 
David Dyer-Bennet, dd-b at dd-b.net; http://dd-b.net/
Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/
Photos: http://dd-b.net/photography/gallery/
Dragaera: http://dragaera.info

Last I had heard, there was no solaris support for port multipliers yet, but I
believe that they plan on supporting it in the future. That said, I think that
the FreeBSD port fully supports it now as well as FUSE on Linux. This
isn''t really a zfs issue, but more of a driver issue.

The other thing to mention is that you can pick up an 8 port sata card for like
100 bucks. That is what I did and managed to find an 8 bay external enclosure,
and connected everything with simple converters that took 8 SATA2 cables down to
2 infiniband cables. This kept things fairly clean outside of the boxes and
allowed for full bandwidth to all drives.  The cabling and case set me back like
200 bucks, so it came in about the same as a port multiplier setup in terms of
costs - and I expect that I have higher IO bandwidth this way.
 
 
This message posted from opensolaris.org

Lars Tunkrans wrote:
> Anyone tried to use ZFS  with this type of box  ? . The new thing about
this one is that
>    it contains a    1x eSATA  to 4x SATA Port multipler 
> 
> 
> http://www.stardom.com.tw/sohotank%20st5610-4s-sb2.htm
Hi Lars,
we don''t currently have support for SATA port multipliers
in the SATA framework. It''s on the roadmap, not quite sure
of the timeline though.


I think you''d be better off, at this point, going for one
of their other offerings such as


http://www.stardom.com.tw/sohotank%20st5610.htm or
http://www.stardom.com.tw/sohotank%20st5650-4s-u5.htm


I''m looking at the ST5650, myself.


James C. McPherson
--
Senior Kernel Software Engineer, Solaris
Sun Microsystems
http://blogs.sun.com/jmcp	http://www.jmcp.homeunix.com/blog

Which 8 bay external case did you end up using?
 
 
This message posted from opensolaris.org

David Dyer-Bennet wrote:
>
> I''m interested in the same question.  I''m looking at what
to use for
> backup from my Solaris file server.  I''ve had rather bad
experiences
> with external Firewire and USB disks, especially in performance
(can''t
> be absolutely sure the problem isn''t with Windows there, though,
or even
> the specific backup software).  So I''m wondering if using the
eSATA port
> to connect to an external enclosure with multiple drives in it might be 
> a winning strategy.  Two external enclosures, alternate monthly for a 
> full backup, say.  I''m tempted to use ZFS on a random selection of
disks
> with no redundancy, as a way to keep costs down. This does of course 
> multiply the chance of a drive going bad and invalidating a big chunk of 
> the backup just when it hurts most.
>   
If you care enough to do backups, at least care enough to be
able to restore.  For my home backups, I use portable drives with
copies=2 or 3 and compression enabled.  I don''t fool with
incrementals, but many people do.  The failure mode I''m worried
about is decay, as the drives will be off most of the time.  The
copies feature works well for this failure mode.
 -- richard

Richard Elling wrote:
> David Dyer-Bennet wrote:
>>
>> I''m interested in the same question.  I''m looking at
what to use for
>> backup from my Solaris file server.  I''ve had rather bad
experiences
>> with external Firewire and USB disks, especially in performance 
>> (can''t be absolutely sure the problem isn''t with
Windows there,
>> though, or even the specific backup software).  So I''m
wondering if
>> using the eSATA port to connect to an external enclosure with 
>> multiple drives in it might be a winning strategy.  Two external 
>> enclosures, alternate monthly for a full backup, say.  I''m
tempted to
>> use ZFS on a random selection of disks with no redundancy, as a way 
>> to keep costs down. This does of course multiply the chance of a 
>> drive going bad and invalidating a big chunk of the backup just when 
>> it hurts most.
>>   
>
> If you care enough to do backups, at least care enough to be
> able to restore.  For my home backups, I use portable drives with
> copies=2 or 3 and compression enabled.  I don''t fool with
> incrementals, but many people do.  The failure mode I''m worried
> about is decay, as the drives will be off most of the time.  The
> copies feature works well for this failure mode.
>

I am definitely and strongly interested in restoring!  That''s why I
hate
my previous backup solutions so much (NTI backup and then Acronis True 
Image); I verified backups and tested restores, and had *FAR* too much 
trouble to be at all comfortable.  The photos and the ebooks are backed 
up eventually (but not always within the month) to good DVDs, and one 
copy is kept off-site, and that''s the stuff I''d miss most if
it went,
but I want a good *overall* solution.

The "copies" thing sounds familiar from discussion here...ah.  Yes, 
that''s exactly perfect; it lets me make up a batch of miscellaneous 
spare disks totaling enough space, each one a vdev, put them into one 
pool (no redundancy), but with copies=2 get nearly the redundancy of 
mirroring which would have required matching drives.   At least, if I 
find a solution for connecting that bunch of disks conveniently.  I 
really want one box with easily swappable disks, and one cable.  (And 
then two of them, since of course I need two sets of backup media to 
alternate between.)  And I could update the old full backup to become 
the new one using rsync locally, perhaps much faster than doing a full CP. 

So how do I get introduced to SAS, and how does that relate to SATA, and 
where does "infiniband" come in (I know of that one only in terms of 
huge expensive switches, does it actually apply to home disk setups at 
all?)?  I''m going to start with Wikipedia tonight, and then see what 
people suggest for further information.

-- 
David Dyer-Bennet, dd-b at dd-b.net; http://dd-b.net/
Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/
Photos: http://dd-b.net/photography/gallery/
Dragaera: http://dragaera.info

Apparently I spent more than my brain wanted me to believe. Here is what I
picked up. Even though I am over the 1 meter limit on SATAII, it worked great.

http://www.pc-pitstop.com/sata_enclosures/scsat84xb.asp


Eric
 
 
This message posted from opensolaris.org

> >
> > If you care enough to do backups, at least care enough to be
> > able to restore.  For my home backups, I use portable drives with
> > copies=2 or 3 and compression enabled.  I don''t fool with
> > incrementals, but many people do.  The failure mode I''m
worried
> > about is decay, as the drives will be off most of the time.  The
> > copies feature works well for this failure mode.
>
> I am definitely and strongly interested in restoring!  That''s why
I hate
> my previous backup solutions so much (NTI backup and then Acronis True
> Image); I verified backups and tested restores, and had *FAR* too much
> trouble to be at all comfortable.  The photos and the ebooks are backed
> up eventually (but not always within the month) to good DVDs, and one
> copy is kept off-site, and that''s the stuff I''d miss most
if it went,
> but I want a good *overall* solution.
>
> The "copies" thing sounds familiar from discussion here...ah. 
Yes,
> that''s exactly perfect; it lets me make up a batch of
miscellaneous
> spare disks totaling enough space, each one a vdev, put them into one
> pool (no redundancy), but with copies=2 get nearly the redundancy of
> mirroring which would have required matching drives.   At least, if I
>From what I have seen I think you are over estimating the value of
copies=x.  copies=X are guaranteed to store multiple copies (X) of the
blocks _somewhere_ in the pool,  but not necessarily on different disks.
So while you may gain mirror like protection when you have failed blocks on
a disk (maybe -- blocks could be too close together on the same disk);  you
do not necessarily gain that from a failed disk (block copies could be on
only one disk). Having different sized unprotected disks and using copies=N
has less mirror like effect over time and fragmentation of those disks.

http://blogs.sun.com/bill/entry/ditto_blocks_the_amazing_tape
http://blogs.sun.com/relling/entry/zfs_copies_and_data_protection


copies < mirrors.
> find a solution for connecting that bunch of disks conveniently.  I
> really want one box with easily swappable disks, and one cable.  (And
> then two of them, since of course I need two sets of backup media to
> alternate between.)  And I could update the old full backup to become
> the new one using rsync locally, perhaps much faster than doing a full
CP.

Wade.Stuart at fallon.com wrote:
>>> If you care enough to do backups, at least care enough to be
>>> able to restore.  For my home backups, I use portable drives with
>>> copies=2 or 3 and compression enabled.  I don''t fool with
>>> incrementals, but many people do.  The failure mode I''m
worried
>>> about is decay, as the drives will be off most of the time.  The
>>> copies feature works well for this failure mode.
>>>       
>> I am definitely and strongly interested in restoring!  That''s
why I hate
>> my previous backup solutions so much (NTI backup and then Acronis True
>> Image); I verified backups and tested restores, and had *FAR* too much
>> trouble to be at all comfortable.  The photos and the ebooks are backed
>> up eventually (but not always within the month) to good DVDs, and one
>> copy is kept off-site, and that''s the stuff I''d miss
most if it went,
>> but I want a good *overall* solution.
>>
>> The "copies" thing sounds familiar from discussion here...ah.
Yes,
>> that''s exactly perfect; it lets me make up a batch of
miscellaneous
>> spare disks totaling enough space, each one a vdev, put them into one
>> pool (no redundancy), but with copies=2 get nearly the redundancy of
>> mirroring which would have required matching drives.   At least, if I
>>     
>
> >From what I have seen I think you are over estimating the value of
> copies=x.  copies=X are guaranteed to store multiple copies (X) of the
> blocks _somewhere_ in the pool,  but not necessarily on different disks.
> So while you may gain mirror like protection when you have failed blocks on
> a disk (maybe -- blocks could be too close together on the same disk);  you
> do not necessarily gain that from a failed disk (block copies could be on
> only one disk). Having different sized unprotected disks and using copies=N
> has less mirror like effect over time and fragmentation of those disks.
>
> http://blogs.sun.com/bill/entry/ditto_blocks_the_amazing_tape
> http://blogs.sun.com/relling/entry/zfs_copies_and_data_protection
>   
Yes, that''s quite clear even just from the man page.  That''s
why I said
"nearly"; I understand that  "copies < mirrors", as you
put it.  Not
*necessarily* on different disks, but it *tries* to put it on different 
disks.  "Over time" isn''t necessarily an issue, since a new
full backup
could be done into a clean filesystem.

-- 
David Dyer-Bennet, dd-b at dd-b.net; http://dd-b.net/
Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/
Photos: http://dd-b.net/photography/gallery/
Dragaera: http://dragaera.info

> Tape drives and tapes seem to be just too expensive. Am I out of date here?
No, I don''t think so.  The problem is that the low-end tape market has
mostly vanished as CDs/DVDs/disks get cheaper -- not that it should, because
tape is much more reliable -- so the cost of entry is pretty high. I use AIT-1
tapes at home, which give me about 35 GB/tape, but I''d be a lot happier
with AIT-3 (100 GB/tape). The tapes are reasonably affordable; unfortunately,
the drives are priced for small business, not for home use.
> What would I need to buy to back up a system that currently has 
> about 600GB of data in it, growing a few GB a month on average?
I''d probably back up everything onto two large (750 GB or 1 TB)
external drives, each kept off-site at a different location. (Being paranoid,
I''d also likely want at least one tape backup, but the initial full
backup would take a long time....)
> Also, what *software* does one use?  For a full, and for an incremental?
I''ve heard of Amanda but haven''t used it.  I suppose there are
other open-source backup solutions.  I use commercial backup software, myself.
> ZFS can give me a view equivalent to an 
> incremental, can''t it?  Which I could then copy
> somewhere suitable?
Hmmm.  I don''t think it exposes such a view right now, though at first
glance it wouldn''t be too hard -- along with a snapshot, you could have
a ''snapdiff'' view, which would only expose the files which had
changed since a previous snapshot.  I think that would be pretty straightforward
to implement....

Anton
 
 
This message posted from opensolaris.org

Where do you get an 8 port SATA card that works with Solaris for around $100?
 
 
This message posted from opensolaris.org

http://www.wiredzone.com/xq/asp/ic.10016527/qx/itemdesc.htm

On Dec 17, 2007 2:01 PM, Tom Buskey <tom at buskey.name>
wrote:
> Where do you get an 8 port SATA card that works with Solaris for around
$100?
>
>
>
> This message posted from opensolaris.org
> _______________________________________________
> zfs-discuss mailing list
> zfs-discuss at opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
>

At the risk of groveling, I''d like to add one more to the set of people
wishing for this to be completed. Any hint on a timeframe? I see reference to
this bug back in 2006
(http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6409327), so I was
wondering if there was any progress.

Thanks!
 
 
This message posted from opensolaris.org

Patrick O''Sullivan wrote:
> At the risk of groveling, I''d like to add one more to the set of
people wishing for this to be completed. Any hint on a timeframe? I see
reference to this bug back in 2006
(http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6409327), so I was
wondering if there was any progress.
>   
This has nothing to do with ZFS, as it is a device driver issue
(hint: category driver:sata)
Perhaps you could ask over in the device drivers community?
http://www.opensolaris.org/os/community/device_drivers/
 -- richard

Right.  I can confirm that using port-multiplier-capable cards works  
on the Mac.  I''ve got an 8-disk zpool with only two SATA ports.  Works
like a charm.

bri

On Jan 17, 2008, at 12:22 PM, Richard Elling wrote:
> Patrick O''Sullivan wrote:
>> At the risk of groveling, I''d like to add one more to the set
of
>> people wishing for this to be completed. Any hint on a timeframe? I  
>> see reference to this bug back in 2006
(http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6409327
>> ), so I was wondering if there was any progress.
>>
>
> This has nothing to do with ZFS, as it is a device driver issue
> (hint: category driver:sata)
> Perhaps you could ask over in the device drivers community?
> http://www.opensolaris.org/os/community/device_drivers/
> -- richard

Thanks. I''ll give that a shot. I neglected to notice what forum it was
in since the question morphed into "when will Solaris support port
multipliers?"

Thanks again.
 
 
This message posted from opensolaris.org