<html><head>
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</head><body bgcolor="#FFFFFF" text="#000000">Are you talking about ZFS
in general or ZoL? The problems I've seen with ZoL is the performance
inconsistencies (review github for details), redundant caching, and of
course user quotas (workaround is zvols but zvols seem to have their own
issues in current ZoL releases). As for redundant caching, data seems
to be cached by the linux page cache and ARC leaving less available for
both. I have yet to talk to someone who is using ZoL in production for
OpenVZ. <br>
<br>
<blockquote style="border: 0px none;"
cite="mid:54646A26.1070406@snajpa.net" type="cite">
<div style="margin:30px 25px 10px 25px;" class="__pbConvHr"><div
style="display:table;width:100%;border-top:1px solid
#EDEEF0;padding-top:5px"> <div
style="display:table-cell;vertical-align:middle;padding-right:6px;"><img
photoaddress="lists@snajpa.net" photoname="Pavel Snajdr"
src="cid:part1.00030608.08070903@virtualcomplete.com"
name="compose-unknown-contact.jpg" height="25px" width="25px"></div> <div
style="display:table-cell;white-space:nowrap;vertical-align:middle;width:100%">
<a moz-do-not-send="true" href="mailto:lists@snajpa.net"
style="color:#737F92
!important;padding-right:6px;font-weight:bold;text-decoration:none
!important;">Pavel Snajdr</a></div> <div
style="display:table-cell;white-space:nowrap;vertical-align:middle;">
<font color="#9FA2A5"><span style="padding-left:6px">Thursday,
November 13, 2014 3:21 AM</span></font></div></div></div>
<div style="color:#888888;margin-left:24px;margin-right:24px;"
__pbrmquotes="true" class="__pbConvBody"><div>Oh, again, this debate
always goes on and on :)<br><br>Guys, try ZFS yourselves and come back
here :)<br><br>You obviously haven't seen ARC caching in action. You
haven't played<br>with snapshots. You haven't seen what the online
compression can do.<br><br>Etc., etc., etc.<br><br>There's lots to ZFS,
which neither BTRFS will ever even remotely approach.<br><br>Try having
this config:<br><br>- 300+ containers on a single node<br>- 128G RAM<br>-
6 spindles, 2 SSDs<br>- run MySQL on at least 50 of the containers<br><br>Not
only it is way too faster than anything you could do with ext4 even<br>if
it's split via ploop into smaller filesystems, it is also much, much<br>easier
to manage. ZFS has a tree structure of filesystems with property<br>inheritance.<br><br>It's
designed to be The Solution for situations exactly like this one.<br><br>The
only shortcoming I can really see and mention from my experience of<br>running
an OpenVZ based hosting with 850 active CTs on top of ZFS, is<br>that
it lacks the support for dquota.<br><br>I've looked into integrating
dquota with ZFS, but it's such an utter<br>mess of an invention, that I
have quickly changed my mind and instead<br>we're just doing more
datasets (== subvolumes in BTRFS). They are really<br>inexpensive (16kB
each), can have own size limits (quotas in ZFS lingo)<br>and thanks to
the tree structure with inheritance it's easy to manage them.<br><br>Also,
forget about rsync and all that crap. Send/receive kills it with ease.<br><br>/snajpa<br></div><div><!----><br>_______________________________________________<br>Users
mailing list<br><a class="moz-txt-link-abbreviated" href="mailto:Users@openvz.org">Users@openvz.org</a><br><a class="moz-txt-link-freetext" href="https://lists.openvz.org/mailman/listinfo/users">https://lists.openvz.org/mailman/listinfo/users</a><br></div></div>
<div style="margin:30px 25px 10px 25px;" class="__pbConvHr"><div
style="display:table;width:100%;border-top:1px solid
#EDEEF0;padding-top:5px"> <div
style="display:table-cell;vertical-align:middle;padding-right:6px;"><img
photoaddress="dowdle@montanalinux.org" photoname="Scott Dowdle"
src="cid:part1.00030608.08070903@virtualcomplete.com"
name="compose-unknown-contact.jpg" height="25px" width="25px"></div> <div
style="display:table-cell;white-space:nowrap;vertical-align:middle;width:100%">
<a moz-do-not-send="true" href="mailto:dowdle@montanalinux.org"
style="color:#737F92
!important;padding-right:6px;font-weight:bold;text-decoration:none
!important;">Scott Dowdle</a></div> <div
style="display:table-cell;white-space:nowrap;vertical-align:middle;">
<font color="#9FA2A5"><span style="padding-left:6px">Wednesday,
November 12, 2014 2:48 PM</span></font></div></div></div>
<div style="color:#888888;margin-left:24px;margin-right:24px;"
__pbrmquotes="true" class="__pbConvBody"><div>Greetings,<br><br>-----
Original Message -----<br></div><div><!----><br>Performance issues
aren't the only problem ploop solves... it also solves the changing
inode issue. When a container is migrated from one host to another with
simfs, inodes will change... and some services don't like that. Also
because the size of a ploop disk image is fixed (although changeable),
the fixed size acts as a quota... so you get your quota back if you
turned it off.<br><br>For me, unless something changes, ZFS isn't a
starter because almost no one ships with it because of licensing issues.<br><br>How
about btrfs? I don't think btrfs is available easily in the existing
OpenVZ kernels... nor in a modular format (like ZFS) so we might have to
wait until the availability of a RHEL7-based OpenVZ branch. Red Hat
still considers btrfs experimental but that may change with upcoming
RHEL7 updates. Both SUSE and Oracle have been using btrfs for some time
although they do not support btrfs' entire feature set... they stick
with the basic features and avoid the less mature ones. Luckily that
includes mirror, checksums, snapshoting, subvolumes, etc.<br><br>I
wouldn't put simfs and ploop in the same column as the underlying
filesystems.<br><br>I'm not sure why the chart says that simfs has
issues with migration. Other than the inode issue, which isn't an issue
with the services I run, simfs actually migrates faster because it
doesn't have to transfer the entire disk image... and if the host has
been migrated before and has a previous copy of its filesystem
available, only the changed files have to be transferred... saving a lot
of time.<br><br>TYL,<br></div></div>
</blockquote>
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