Fabio Zetaeffesse
2015-02-23 11:05:44 UTC
Hi there,
I've just subscribed and read many posts on this list because I'd like to
build my own pool/vdev. I'm still learning but I would like to put my hands
on ZFS.
That's why I'd like to go for a RAIDZ2 with 5 units and I'd like to go for
HGST disks after having read the BackBlaze report (see my question 2), I
prefer reliability over performance, after all ZFS is born having that in
mind, no?
My pool won't have to perform a lot and I rather go for the most silent and
least consuming, in terms of power, drives. Basically what normally people
would call such a pool THE BACKUP pool for me it will be THE pool :)
I have some of questions, I apologize in advance if the majority of them
look at newbie level :) :
1) do I really need SSDs for the cache/log? Can I share SSDs for both? I
see some practice this. Looking at some models I read compressible (ATTO
used by Kingston for instance) vs. non-compressible (S-SSD and
CrystalDiskMark yet Kingston's terms) transfer rate. whilst the first is
very high (400-450 Mb/s) the second is low even lower of a hard disk. I'm a
bit confused :-) 'cause I know SSD are faster then HDs. Which parameters do
you take into account when choosing a SSD?
2) though outdated I found HDS722020ALA330 for 80⬠each.Its claimed
transfer rate is 200 Mb/s whilst the transfer rate of newer disks with
6Gbits/s interface and 4TB or 6TB capacity is just a bit higher (230 Mb/sec
and their price is double) So I won't benefit in buying models with
6Gbit/sec. Am I correct?
3) While transferring a big file (say 40-50Gb) might the ZFS cache be a
limit? I mean the transfer rate toward the cache is as the same as towards
the disk but via the cache I have two steps and I double the flows through
the controller, am I right? If I'm right is there a way to bypass the cache
for certain transfers?
4) if I have to replace a disk (from what I've read it's not as easy as it
might seem detecting such faulty disk) I'll have to replace it and resilver
it, but what if I have to do the same for a cache/log? Normally for the
cache I'd choose for the mirror model.
Thanks,
Alex
To unsubscribe from this group and stop receiving emails from it, send an email to zfs-discuss+***@zfsonlinux.org.
I've just subscribed and read many posts on this list because I'd like to
build my own pool/vdev. I'm still learning but I would like to put my hands
on ZFS.
That's why I'd like to go for a RAIDZ2 with 5 units and I'd like to go for
HGST disks after having read the BackBlaze report (see my question 2), I
prefer reliability over performance, after all ZFS is born having that in
mind, no?
My pool won't have to perform a lot and I rather go for the most silent and
least consuming, in terms of power, drives. Basically what normally people
would call such a pool THE BACKUP pool for me it will be THE pool :)
I have some of questions, I apologize in advance if the majority of them
look at newbie level :) :
1) do I really need SSDs for the cache/log? Can I share SSDs for both? I
see some practice this. Looking at some models I read compressible (ATTO
used by Kingston for instance) vs. non-compressible (S-SSD and
CrystalDiskMark yet Kingston's terms) transfer rate. whilst the first is
very high (400-450 Mb/s) the second is low even lower of a hard disk. I'm a
bit confused :-) 'cause I know SSD are faster then HDs. Which parameters do
you take into account when choosing a SSD?
2) though outdated I found HDS722020ALA330 for 80⬠each.Its claimed
transfer rate is 200 Mb/s whilst the transfer rate of newer disks with
6Gbits/s interface and 4TB or 6TB capacity is just a bit higher (230 Mb/sec
and their price is double) So I won't benefit in buying models with
6Gbit/sec. Am I correct?
3) While transferring a big file (say 40-50Gb) might the ZFS cache be a
limit? I mean the transfer rate toward the cache is as the same as towards
the disk but via the cache I have two steps and I double the flows through
the controller, am I right? If I'm right is there a way to bypass the cache
for certain transfers?
4) if I have to replace a disk (from what I've read it's not as easy as it
might seem detecting such faulty disk) I'll have to replace it and resilver
it, but what if I have to do the same for a cache/log? Normally for the
cache I'd choose for the mirror model.
Thanks,
Alex
To unsubscribe from this group and stop receiving emails from it, send an email to zfs-discuss+***@zfsonlinux.org.